RADIO FOR ALL
THE FUTURE OF RADIO
IN this illustration are shown some of the future wonders of Radio. Several
of the ideas are already in use, in an experimental way, and it should not be
thought that the entire conception is fantastic.
The illustration shows a business man, let us say, fifty years hence. To the
right is a television and automatic radiophone. By means of the plug shown
to the right of the machine, the man can plug in any city in the United States
he desires ; then, by means of this automatic control board he can select anv
number in that city he wishes, merely by consulting his automatic telephone
directory. As soon as he has obtained his number, a connection is made auto-
matically and he not only can talk, but he can see the party whom he calls. At
the top of the instrument is a loud-talker which projects the voices of the people,
while on a ground-glass in front of him the distant party is made visible. This
idea is already in use, experimentally.
Directly in front of the man, we see the "radio business control." By means of
another television scheme, right in back of the dial, the man, if he chooses to do
so, can load and unload a steamer, all by radio telemechanics, or throw a distant
switch, or if a storm comes up, look into the interior of his apartment and then,
merely by pressing a key, pull down the windows; all of which can be accom-
plished by radio telemechanics, a science already well known.
His business correspondence comes in entirely by radio. There is a tele-
radio-typewriter. This electro-magnetic typewriter can be actuated by any one
who chooses to do so. For instance, if we wish to write a letter to Jones &
Company, Chicago, Illinois, we call up by radio, that station, and tell the operator that
we wish to write a letter to the Company. Once the connection is established,
the letter is written in New York, let us say, on a typewriter, and automatically
sent out through space by radio; letter for letter, word for word being written
by the other typewriter in Chicago. The letter when finished falls into a basket.
Instead of sending our correspondence by mail we shall then do our letter-writing
by radio. There is nothing difficult about this scheme, and as a matter of fact, it can
be put into use today, if so desired. We have all the instrumentalities ready.
Going further, we find the Radio Power Distributor Station that sends out
power over a radius of 100 miles or more. This radio power may be used for
lighting, and other purposes.
In front of the bridge we see a number of people who are propelled by
Radio Power Roller Skates. On their heads we see curious 3-prong metallic
affairs. These collect the radio power from a nearby railing, which, however, is
not in view, and which they do not touch. The power is sent through space from
the rail to the 3-pronged affair and then is conveyed to the skates, which are
operated by small electric motors. The<e roll at the rate of 15 to 20 miles an
hour, and there is no visible connection between the wearer and the Radio
We next see the crewless ships controlled by radio. This has been made pos-
sible today. Indeed, several U. S. battleships have already been manoeuvred over
a considerable distance by radio. The time will come when we can direct a ship
across the ocean without a human being on board. Future freight will be sent
in this manner. The ship, every ten minutes, gives its location by radio, so that
the land dispatcher will know at any time where the ship is located. Collisions
are avoided by a number of instruments into details of which we need not go here,
but which have already been perfected. Collision with icebergs also is avoided
by thermo-couples which divert the ship away from the iceberg as soon as it
enters water which has been cooled below a certain degree.
The radio-controlled airplane works similarly to the radio-controlled ship,
and it will be possible to control such airships very readily in the future. As a
matter of fact, John Hays Hammond, Jr., in this country, has done this very
thing. Radio-controlled airplanes will play a great role in the next war.
It is a mistake to think that radio is only good for the distribution of intel-
ligence. As the illustration shows, the great uses of radio have not been touched
upon as yet.
RADIO FOR ALL
EDITOR OF "RADIO NEWS"
WITH 13 HALFTONES AND 138 ILLUSTRATIONS
PHILADELPHIA & LONDON
J. B. LIPPINCOTT COMPANY
COPYRIGHT, 1923, BY J. B. LIPPINCOTT COMPANY
PRINTED BY J. B. LIPPINCOTT COMPANY
AT THE WASHINGTON SQUARE PRESS
PHILADELPHIA, U, S, A,
IN writing the present volume the author has
continually had in mind a book for the public at
large, not acquainted as yet with the radio art.
After having reviewed nearly all the recent books
on radio that have appeared since radio took
the public's fancy, the author believes that the
present volume covers ground not touched upon by
The keynote of the book has been simplicity in
language, and simplicity in radio. This book,
therefore, is not a technical volume, and wherever
possible all technicalities, all mathematics, and all
abstruse subjects have been left out entirely. It will
also be noted that the author has not made
use of the word "ether" in this book; for the
reason that modern scientists are no longer
in sympathy with the ether theory. The vacuum
tube, it will be noted, has been touched upon very
lightly and only where it was absolutely necessary.
The reason is that the vacuum tube is a highly tech-
nical subject, and therefore does not belong in this
book. It is a science by itself.
The author has always been a great believer in
analogies to drive a point home ; and for this reason
analogies have been made use of freely wherever
possible in this volume.
His experience in editing the first radio
journal in the United States, Modern Electrics,
in 1908, then later, Electrical Experimenter, (now
Science and Invention), and, still more recently, as
editor of Radio News, has given him the opportunity
to view the radio problem through the eyes of the
"man in the street." He hopes that he has suc-
ceeded in conveying a technical message into
If the present volume is the means of converting
a fair percentage of the public at large to radio,
the labor expended has been well worth while.
New York, June, 1922
I. HISTORIC 11
II. WAVE ANALOGIES 15
III. TRANSMITTING (GENERAL) 30
IV. RECEIVING (GENERAL) 42
V. RECEIVING INSTRUMENTS 51
VI. TUNING 101
VII. AERIALS, LOOP AERIALS, GROUNDS 108
VIII. RADIO DIAGRAMS AND How TO READ THEM 149
IX. RADIO TELEPHONY 164
X. How TO MAKE SIMPLE RECEIVING OUTFITS 180
XI. THE FUTURE OF RADIO 229
XH. RADIO ACT pyj912.... 239
LIST OF ILLUSTRATIONS
The Future of Radio Frontispiece
Transmitting President Harding's Arlington Address 42
Amplifiers Used to Receive the Speech 42
Motorbus Equipped With Radio 70
Two Portraits Transmitted by Radio 101
The Author's Radiotrola 127
Mme. Olga Petrova Singing for Radio 149
Mme. Gadski Singing Tannhauser Aria 164
Broadcasting Station Power Plant 173
Author Delivering Lecture From Newark 229
Power Plant of Newark Broadcasting Station 239
Map U. S. Radio Broadcasting Stations 282
RADIO FOR ALL
LET us begin at the beginning. There are so
many misconceptions in radio today that it is best
that the reader should know just how the art of
radio came into existence. The true art of radio
was unquestionably discovered by Heinrich Hertz,
a German professor, living at Frankfort. His first
technical papers on his epoch-making invention were
published in 1887. Hertz's experiments were chiefly
made in the laboratory. Years before, Maxwell had
made the statement that light waves and electric
waves were all of the same order. There had,
however, before Hertz's time never been any experi-
ments of electric waves in free space. Hertz was
the first to send electric waves through space
by means of an electric spark. His appara-
tus was simple; he had an electric spark coil that
made intermittent sparks, and by proper arrange-
ment of this station, he could receive sparks at a
distance by the simple arrangement of cutting a
single wire hoop and leaving a small gap. Between
the two free ends, small sparks jumped whenever
sparks were made to jump on his spark coil a few
yards away. In other words, every time he pressed
13 RADIO FOR ALL
the key at his sending station, a spark would jump
at the small gap at his receiving station, which was
composed of nothing but a wire hoop. This con-
clusively proved that electric or, better, electro-
magnetic waves had been sent through free space.
His were only laboratory experiments, and while
he described the phenomenon correctly in scientific
papers, and while it was even in these days consid-
ered an epoch-making discovery, no one thought
of using the invention for practical purposes.
However, Guglielmo Marconi, an Italian youth
had read of these experiments, and being gifted
along these lines, he duplicated Hertz's experiments.
Soon his mind conceived the idea of using the inven-
tion for transmitting intelligence over a distance.
He endeavored to send a message without wires over
miles where Hertz used yards. Instead of the wire
hoop, Marconi devised and used a more sensitive ap-
paratus. He found that an instrument called the
coherer was enormously sensitive to the new electric
waves, and he soon was transmitting signals for
many hundreds of yards on the estate of his father
in Italy. By diligent labor he increased this dis-
tance, and shortly was telegraphing without wires
across the English channel, and not many years
later, he transmitted the letter "S" in telegraphic
code across the Atlantic by means of wireless.
To Marconi, therefore, belongs the honor of
having perfected the wonderful invention of radio,
first discovered by Hertz. Radio telephony, con-
trary to popular opinion, is not a new invention
either. It has now been known for over two dec-
ades. Radio telephony, as we know it today, was
first invented by Valdemar Poulsen, the Danish
Edison. Instead of using a crashing spark at his
sending station, he used a silent electric arc with
certain adjuncts. This was not only entirely noise-
less, but it gave rise to something new, viz., Contin-
uous Waves. Heretofore, radio engineers had al-
ways used the electric spark which produced inter-
rupted waves. With these sparks, we could not
transmit the human voice because the interrupted
waves would break up the words in such a way
that nothing intelligible could be heard at the re-
ceiving station. It is as if you were trying to talk
and somebody was vibrating the hand to and from
the mouth rapidly. Naturally, no intelligible
words can be heard when this is done. Since
Poulsen's time, radio telephony has been well known
to the radio fraternity and many messages have been
sent. Thus for instance, in 1915, words spoken at
the Eiffel tower station, Paris, were distinctly heard
in Arlington, which is on the outskirts of Washing-
ton, D. C. At another time, the human voice flung
out into space at Arlington, was heard distinctly
at Honolulu, a distance of over 5000 miles. So
you see, the art of radio telephony is not of recent
origin, as people still believe. Not only is it possi-
ble to send the human voice from one radio trans-
mitting station to a radio receiving station, but in
14 RADIO FOR ALL
1916, an experiment was made whereby people sit-
ting in the dining room of the Waldorf Astoria
could hear the sound of the surf of the Pacific Ocean
at San Francisco, a distance of over 3000 miles.
This was accomplished by hooking up the radio sta-
tion to the ordinary land station, while the radio re-
ceiving station was at Arlington, Va. Then the radio
waves were conducted along an ordinary telephone
wire stretched between Washington and New York,
and the roar of the ocean was heard through the
ordinary telephone receivers connected to the tele-
phone switchboard in the Waldorf Astoria. The
public for many years refused to be interested in
radio telephony until very recently, when our broad-
casting stations began to send out regular enter-
tainment by radio. Then the newspapers began to
take it up, and today radio is a household word in
every American home, be it located in the city, the
suburbs or in the country.
FIRST of all it is necessary that you implant
thoroughly into your mind the fact that there is
nothing mysterious about radio; it is subject to
natural laws the same as other phenomena.
What is a radio wave? It is not any different
physically than a sound wave or a wave in the ocean.
If we throw a heavy stone in a still lake, it makes
what we call a splash. This wave rapidly extends in
the form of circles, as shown in Fig. 1. The heavier
the stone and the higher it falls, the greater the
splash, and the higher the waves. It is exactly so in
16 RADIO FOR ALL
radio. If by means of certain electrical apparatus
connected to an serial, we excite this serial electri-
cally, waves are set up in the space exactly as water
waves are set up on the lake. Radio waves, just as
do the water waves, branch out in all directions.
With the water waves this is not so true. A true
water wave, as we know, is carried along only upon
the surface of the water. A few feet below the water
and immediately above the water, no water waves
are had. A more strict analogy would be
sound waves. Take for instance, a church bell.
By giving it a blow with a hammer, we excite this
bell. What happens? Sound waves are set up
in the air in all directions from the bell. Whether
you are on the street level, 100 feet below, whether
you are 100 feet above in an airplane, whether you
are in a building where it is on the same level as
you are in all these positions you will clearly hear
the ringing of the bell. (Fig. 2.) What does this
mean? Just this. The sound waves are propagated
in every direction in
the form of waves,
invisible to the
eye, but "visible"
to the ear. These
waves are exactly
of the same shape
as are the ocean
waves or water
waves with the
difference that the
sound waves go
out in the air in
the form of
spheres. In other
words, the first
sound wave leav-
ing the bell F '-
would be a sort of invisible globe all around it. The
wave rapidly branches out, becoming larger and
larger, always remaining, however, in the form of a
sphere, as seen in Fig. 3. If the sound waves do not
go out in the form of spheres, it would not be possi-
ble for us to hear them in all directions as we have
seen in Fig. 2. We, therefore, come to the conclusion
18 RADIO FOR ALL
that sound waves that leave a bell branch out,
above, below, sideways, in fact in all directions.
It is exactly so in radio. The serial of the
broadcasting station, or other radio transmit-
ting station radiates exactly as does a bell. Both
are transmitters of waves. The radio waves go
out in the form of spheres as well, branching out
in every direction of the compass, as well as below
and above. Not only do the radio waves pass
through the air the same as the sound waves, but
radio waves pass through solid objects also, in an
easier manner than sound waves.
We all know that we can hear a bell even if
windows are closed. In other words, the invisible
sound waves pass through the window panes al-
though we cannot see the sound waves. Radio
waves do exactly the same thing, with the exception
that they pass through solids far better than do
sound waves. If we are far down in a basement, and
providing it is sound proof, we no longer hear the
bell, but radio waves go through solid stone walls
with great facility, and are, therefore, not stopped
by such obstacles. Radio waves even pass through
mountains, providing these mountains do not con-
tain ores or other metallic substances. Radio
waves also pass through the water just as sound
waves do. We all know that if we suspend a bell
below water, it may be heard if we sink a tube into
the water and apply our ear to it. Thus radio
waves may be received in submarines totally sub-
WAVE ANALOGIES 19
merged in water. Radio waves also pass through
the earth with great facility. As a matter of fact,
it is possible to receive radio messages readily, as
we will see in a later chapter, by burying an insu-
lated wire in the ground. Such a wire, though
deeply buried, readily intercepts radio messages.
We therefore have learned here that there is
nothing mysterious about the radio waves any more
than sound waves. Both are subject to similar
natural laws. Not only this, but as we all know
the farther away we go from a ringing bell, the more
difficult it is to hear it. The greater the distance
the less able we are to hear the bell. The reason is
of course, that the original wave, as we increase the
distance between ourselves and the bell, becomes
larger and larger and soon covers a tremendous dis-
tance. Finally there comes a point where we no
longer can hear the bell. This may be a distance of a
mile or less, that is if we have ordinary hearing.
There are, however, persons and animals whose
hearing is so acute that they can hear the same
bell much further by reason of their being
If we were to take two horns and point them in
the direction of the bell, as shown in Fig. 4, and
apply the ear pieces to our ears, we would be able
to hear the bell again, although without these appli-
ances, we would not be able to hear it at all. Why is
this so? The reason is that the vibrations that
reach our ears normally are too weak to be inter-
RADIO FOR ALL
cepted by our small ears. By enlarging our ears,
as shown in Fig. 4, we intercept many more weak
sound waves, and these waves, all being collected
into our ears bunched together, so to speak are
sufficient to again impress the diaphragm in the ear,
and we are thus again enabled to hear the sound.
We merely cite this interesting experiment because
it holds true in radio as well. If we have a
transmitting station, or a broadcasting station, we
can hear it only up to a certain distance with a given
apparatus. If we take a small aerial, which we can
liken to a normal ear, we can use it only for a given
distance, let us say 25 miles. If we move this aerial 30
miles away from the radio broadcasting station, we
can no longer hear it. The case here is exactly as
with the sound waves. The radio waves have now to
cover enormous areas, and there are not enough
WAVE ANALOGIES 21
waves, so to speak, to leave any impression upon
our small serial. If, however, we were to double or
triple the size of the serial, we would do physically
the same thing as we were doing when we attached
the two horns to our ears. By having a larger
increased serial with more wires, we would, by
means of this, intercept more waves than we could
with a small normal serial; consequently with such
an serial we could hear the broadcasting station
again, even though we were removed 35 miles from
it. You see that the analogy between the sound
wave and the radio wave holds pretty true, all the
way through. Of course, in radio we have other
means to bring in the signals even if we are removed
still greater distances. It would not always be
practical to make the serial tremendously large in
order to hear greater distances, also we would not
expect to hear our bell 20 miles away by means of
even large horns. We would have to devise some
other more sensitive means to hear the bell, and
there are such means at hand today in super-
sensitive electrical microphones which magnify the
very weakest sounds. So too in radio it is not
necessary to build a larger and larger serial, the
more we remove ourselves from the broadcasting or
transmitting station. Instead, we use more sensi-
tive apparatus which will magnify the sounds in an
electrical manner, so that we can hear the station
even though we are removed thousands of miles
RADIO FOR ALL
What do we mean by wave length? We often
hear in radio that a certain station transmits at a
given wave length, say 360 meters. What does
this mean? First we might state that a meter is a
measurement the same as the yard. A meter,
roughly speaking, measures 40 inches. All Euro-
pean countries instead of yard, foot and inch use the
meter, centimeter and millimeter. The meter has
one hundred centimeters and one thousand milli-
meters. Let us now return to our stone which we
dropped into the water. If we were to place our
eye on a level with the water, and someone was to
throw a stone into a quiet surface of water, what
would we see? Fig. 5 shows this. We would see
a wave coming out, as shown in our illustration.
Any water wave is composed of two distinct parts,
the crest and the trough. In other words, the water
first comes up then dips below the original surface,
then up again above the original surface, etc. In our
illustration, we have shown in dotted lines the orig-
WAVE ANALOGIES 23
inal surface of the water. The disturbance of the
stone has caused the water to expand into waves.
Now then, the wave length is that portion which ex-
tends from crest to crest. In Fig. 5 we see what a
wave length consists of. It starts at the top of the
crest, covers the trough and again up to the crest.
This is exactly one wave length, because it embraces
the total make-up of one complete wave.
By throwing an ordinary stone into the water,
such a wave length may be anywhere from one foot
upwards. Out on the ocean where we have very
large waves, so called swells, such ocean waves may
reach the length of about 300 yards or 100 meters
or more. We might, therefore, say that an ocean
wave has a wave length of 100 meters.
In radio we have the same sort of waves, and
these waves go out into space in all directions, as
we have learned before. In radio we can make a
wave length from a few yards or a few meters up
to several thousand meters and over. This all de-
pends upon the apparatus we use. It would be
the same with our bell. A very small bell, only a
few inches high, would give very small sound waves,
while one of the big church bells would give a much
bigger sound wave. In radio too we have the same
thing, and we can change from a short to a long
What are the different wave lengths used in
radio? It has been found that short waves do not
travel over such great distances as long waves do.
24 RADIO FOR ALL
Using receiving instruments of an ordinary sensitiv-
ity, it has been found that it is better to use a wave
of 2000 meters or more, if we wish to transmit mes-
sages over several thousand miles, as for instance
across the ocean. A small wave length does not
pass as readily over such great distances.
RADIO TELEGRAPH AND RADIO TELEPHONE WAVES
How do the waves in radio telegraphy and radio
telephony differ? In radio telegraphy we simply
hear the plain wave in our telephone receivers, if
thus we may term it. If the operator in the trans-
mitting station presses his key, groups of waves are
sent out into space as long as the key is depressed.
At the receiving side we hear the waves making a
buzzing sound for the length of time that the key is
depressed at the sending station. If the key is
pressed down for a second, we .hear a buzz for a se-
cond. If the key is depressed for two seconds we
hear the buzz for two seconds, and by means of this
buzzing sound the telegraphic signals are repro-
duced^ Usually a code such as the Morse or the
Continental is used. For instance, a short buzz will
be the letter "E" while "SOS" would stand for
the following (a short dash be-
ing a short buzz, a long dash being a long buzz).
In radio telephony, however, we have a different
and more complicated action. In the first place,
we hear sounds, words, and music exactly as they
are produced at the broadcasting or transmitting
station. Two distinct things happen. The aerial
WAVE ANALOGIES 25
is made to send out a radio wave that is continuous.
This wave cannot be heard by the human ear with
ordinary receiving apparatus. It is what is techni-
cally called C.W. or Continuous Wave. It is also
used to carry along the human speech. At this point
we must resort again to our water wave. Suppose we
throw a stone into a river. At the same time that the
stone is thrown we also throw a cork into the water,
at the same spot. What happens? The cork is
carried along by. the current as shown in Fig. 6.
First we see the cork in position 1 . A little later we
see it in position 2. Still later in position 4 as
shown on the dotted lines. The cork, therefore, is
carried along by the wave as well as by the current.
As the waves progress, the cork progresses also.
Exactly the same thing happens when the human
speech is impressed upon the radio carrier wave.
By certain means too technical to go into here, the
26 RADIO FOR ALL
vibrations made by the voice are carried along upon
the carrier wave, exactly as the cork is carried upon
the water wave. At the receiving side we only hear
the words or music, for the reason that the carrier
wave is inaudible. Hence, nothing but the words
or speech are heard by us in our receivers.
SPEED OF WAVES
It might not be amiss to say a few words about
the speed of waves in general. If we drop a stone
into the water, we all know that the speed at which
the waves spread out is rather slow a few feet per
second as a rule is all. Sound waves on the other
hand travel at the rate of 1,100 feet per second. The
speed of sound waves we therefore see, is consider-
ably in excess of that of water waves.
Radio waves travel with the speed of light,
namely, the enormous speed of 186,000 miles per
second. We, therefore, can understand that if a
message is sent out anywhere on our globe, it will
be received at any place almost instantaneously; the
greatest distance that a radio wave or a message
could travel over would be 12,000 miles, for the rea-
son that the circumference of the earth is 24,000
miles. You will see, therefore, that a radio wave
would travel around the earth at the rate of almost
eight times in one second, and, although a radio
message was received over a distance of 12,000 miles,
it would be received in a small fraction of a second,
too small to measure. For practical purposes,
therefore, a radio message sent out from no matter
WAVE ANALOGIES 27
what distance on earth may be said to cover the
POPULAK MISCONCEPTION AS TO RADIO WAVES
Many people have an idea that radio waves
broadcasted by a transmitting or broadcasting sta-
tion, change their form as they are sent out into
space. Many people think that, when we speak of a
360 meter wave length, that this has something to do
with the distance of the sending station or of the
distance that the radio waves cover. Nothing
could be more erroneous. It should be thoroughly
understood that if the Pittsburgh broadcasting sta-
tion is sending out a message transmitted on a 360
meter wave, the length of the wave will remain 360
meters no matter how far it travels. A ship out
on the ocean 3000 miles away from Pittsburgh may
hear the Pittsburgh station ; it will be necessary in
order to hear it to tune the receiving instruments to
360 meters, otherwise Pittsburgh cannot be heard.
Therefore, no matter how far a radio wave travels,
it does not change its length. This is true of every
wave no matter what its length, whether 100
meters or 5,000 meters. The length of the wave
never changes between the transmitting and the
As we have seen before, the different wave
lengths are purely arbitrary. For instance, the wave
length of 360 meters has been chosen only be-
cause it does not interfere with the radio amateurs
who transmit on a wave length of 200 meters, and
28 RADIO FOR ALL
the ship stations which send out on about 600 meters.
It stands to reason that if all stations were to send
at exactly the same wave length, we would get noth-
ing but a jumble.
To elucidate: Suppose you have six pianos in
one room, which are all tuned alike ; if we have six
players sitting down at the pianos and each hits the
same key, we will only hear that one note, let us say
A. You could not possibly detect it if five were
striking the key A, because all of the players are
transmitting on the same sound wave length which
transmits only the note A. Suppose, however, that
one operator is striking the key A while another
strikes the key E. We can immediately eliminate
one or the other, and by a little concentration of
our ear, we can hear either A or E. In other words
the two pianos are now transmitting at different
sound wave lengths, the wave length of E being
different from the wave length of A, and vice versa.
We can go still further in the analogy. Suppose
one person plays a tune on the low treble, while at
the same time another person in the same room plays
a different tune on the high treble. With a little
concentration we can listen to one tune or to the
other. Of course, if we pay no strict attention we
will hear both pianos play simultaneously. It is ex-
actly as if two people talk at the table at the same
time. You can listen to one and shut off your mind
from the other speaker as you well know. In other
words, you are "tuning out" the unwanted speaker.
WAVE ANALOGIES 29
It is exactly so in radio, only we have better means
in radio because we can tune out entirely one sta-
tion or another by means of tuning appliances so
that we can hear either one at will. That is the
reason why different transmitting stations send on
different wave lengths. It is purely an arbitrary
arrangement so as not to confuse the various receiv-
We have learned something in the previous chap-
ter about transmitting. We will now go a little
further, but must be a little more technical here.
There are several ways of transmitting by radio;
the oldest and historical method is shown in Fig. 7.
Here we have an ordinary spark coil such as is used
in automobiles, a few dry cells, a key and the so-
called spark gap which may consist of wire nails
or better two zinc balls. Every time we press the
key a spark jumps across the open space in the spark
gap. By connecting one end of an serial to the
spark gap and the other end to the ground, which
may be a water pipe, or a steam radiator, radio
waves are sent out into space. This is the original
arrangement that Marconi used for transmitting
messages. The serial or antenna used here may be
of any size or shape. The one which we have shown
is a simple single wire, which may be 50 or 100 feet
long. Such a little station as this may be used to
send a radio message over several miles. A station
of this sort, however, is very crude because it is un-
tuned; by this we mean, first, that it sends out
WIRE SOUND BOX
impure waves. We might compare this to a string
held between two nails and plucked with the finger,
when we would hear some sort of noise. In other
words, it would be an impure wave. We might
mention, by the way, that an impure wave is one
that has several notes mixed up with the fundamen-
tal note that gives rise to a noise rather than to a
note, see Fig. 8. Now turn to Fig. 9 ; here we have a
wire stretched very taut between two nails on a
sound board such as an empty box. By tightening
the wire we get a pure or clear note similar to that
32 RADIO FOR ALL
produced when we pluck a string on a violin or a
mandolin. We all know that the violinist, before
beginning to play, has to tune his violin before play-
ing in order to get a pure note. This is his way
of tuning up an instrument. Referring back to
our description of simple radio transmitting, as
shown in Fig. 7, this sends out what we might term a
radio noise, but not a pure radio note. Furthermore,
it is found that if we should take a short metal wire
and stretch it taut, it would give a very high note.
Thus, we know that on a harp for instance, the
highest note will be the short strings and the deep
bass notes will be the long strings. It is exactly
so in radio. In other words, a long serial will give
a long wave length, while a short serial will give
a short wave length.
Just exactly as a manufacturer of a piano knows
what the sound wave length of the longest string of
his piano is, so the radio engineer will know on
what wave length a given aerial will send.
Roughly speaking, an serial 100 feet long will
give a wave length of about 140 meters, while an
serial 200 feet long will give a wave length
of exactly twice the length of the shorter one or
Suppose, with our little outfit shown in Fig. 7,
we wish to send out a wave length of a thousand
meters; we could do this by making an serial
833 feet in length. That, however, would not be
practicable because not in all instances could we
find that much room for the serial.
We, therefore, resort to another means, and we
build an serial indoors which we attach to the orig-
inal serial, a sort of a sending tuning coil, which
we show in Fig. 10. This tuning coil is the same
WATER PIPE GROUND
wire which we use for the serial, wrapped around a
frame or tube, as shown in Fig. 10. This coil
means simply the additional wire which is neces-
sary to lengthen our serial in order to make it long
enough to give us our thousand meters. By means
of the slider, which runs up and down the wire
convolutions, we now have the means of changing
the wave length merely by adding more or less wire.
If this is not entirely plain, take a violin as an ex-
ample. When the violinist wishes to transmit a
certain sound wave he plucks his string first without
34 RADIO FOR ALL
touching his hand to it. As he presses down
on the string, he automatically makes it shorter and
shorter, and the further down his fingers slide, the
higher and higher the note becomes. He does here
exactly the same thing as the slider does on our
coil, that is, he
words, if he
SHORT SOUND LONG SOUND win+c a Inner
WAVE WAVE wants a long
FlG - 1L sound wave he
slides his finger down the small end of the violin,
and if he wants a short sound wave, he slides his
finger towards his chin. This changes the sound
wave length in exactly the same way as our sending
coil changes the radio wave length. Both are fun-
damentally the same.
When Marconi first rigged up his little sending
station, as shown in Fig. 7, he naturally could only
send out radio telegraphic signals. Every time he
pressed the key, radio waves were sent out. When
he pressed the key for a second, a buzzing noise was
heard for a second in the distant receiving tele-
phone receivers. If he pressed the key for two
seconds, a buzzing sound for two seconds was heard.
By this means the telegraphic code is made up, as
shown in Fig. 12. At the present time, the Conti-
nental code is used almost exclusively, and today,
a- 1 ;?
y /*: >
ABBREVIATED NUMERALS U5ED BY CONTINENTAL OPERATORS
t mm aoiHB5e*BHi -4 5 e
ean T *a 8 9MB* to MB
G.E.-GOOD EVENING 4--PLEASE START ME,WHEPE
0.N. NIGHT 3O-NO MORE
GM. MORNING TS'BEST REGAfeDS
G.A. GO AHEAD
D.H. FREE MESSAGE
O PR. -OPERATOR
S.O.S. <=>* <
36 RADIO FOR ALL
as in Marconi's time, when the operator at his send-
ing outfit presses down his key for a short duration,
this is interpreted as a dot at the receiving side, and
when he presses his key down for a longer period
this becomes a dash on the other end. By means of
dots and dashes, the telegraphic code is made up.
It is not the easiest thing to learn this code; it
requires practice, the same as playing a piano or
operating a typewriter. It must be learned, and it is
just as important to learn to send as to receive.
Of course, as soon as we have mastered sending, it
is simple to receive, although, as we might suspect
every operator has his individual characteristic. For
instance, some of the operators, particularly the
good ones, will space the dots and dashes in a certain
clear manner, while others will run the signals to-
gether, making it very difficult for the operator at
the receiving end to get the correct message. Some
operators will go very fast, while others will go
slowly. Soon it becomes possible for operators to
recognize each other simply by their "hand." In
radio telegraphy each sending operator has a
sort of telegraphic "voice" easily recognizable by
In Fig. 7, we showed a simple sender. Of course,
it goes without saying that soon after Marconi
started his experiments, more complicated sending
apparatus was designed. It was found, for in-
stance, that the spark sent out by such a station was
received at the other end very mushy and not at all
clear. It was nothing but a noise. Soon new
apparatus was invented, such as, for instance, a
quenched spark gap which clarified the sound to
such an extent that instead of hearing a mushy,
noisy spark at the other end, a clear whistle or flute-
like sound was received. It was found that such a
spark carried much further and could be worked
readily through static, which is the bane of the radio
telegrapher. Static, by the way, as we will see later
is an atmospheric, electrical disturbance in the air
which makes receiving very difficult at times.
There are now many different transmitters in
use, as for instance, the electric arc which may be
used for transmitting. This has the advantage of
giving rise to what is called continuous waves ; this
is made clear by the diagram shown in Fig. 13.
When we press the key of the old Marconi outfit,
we send out into space radio waves which have some-
what the form shown in Fig. 13. These waves start
with a high pitch, as we might say, and die out rapid-
ly. This happens a great many thousand times
each second, but these waves are not continuous.
They are small wavelets, as we might term them,
which are disrupted and do not form a continuous
line. Look at Fig. 14; this is what we might term
a continuous wave, and is a wave which is sent out
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by an arc transmitter and by a vacuum tube trans-
mitter such as is now used universally at broadcast-
ing stations. As long as the arc from the sending
set is transmitting, a continuous wave is sent out
into space which does not vary. It does not take
a technical mind to know that the waves sent out, as
shown in Fig. 14, must be better and clearer than
the interrupted waves sent out in Fig. 13. As a
matter of fact, the interrupted wave or the wave
made by the spark is coming into less and less use
as time goes by. This is the day of the Continuous
Wave commonly called C. W. It is the Continuous
Wave that makes radio telephony possible.
Let us make a comparison again, which can be
easily understood, and which may serve to make the
interrupted wave and the Continuous Wave clear
in our minds. Take a number of pipes as shown
in Fig. 15 ; one person stands at one end and another
at the other end. One talks into this interrupted
pipe, which may be 100 feet long, and as will be read-
ily seen the person at the other end will have a great
disadvantage in hearing the speaker because the
pipe, being interrupted so many times, breaks up
the speech. This is the analogy for spark waves.
Now turn to Fig. 16; here we have a long pipe,
the same as we use in our speaking tubes, which is
free from interruptions, and is continuous all the
way through. You can readily understand why the
person at the other end will have no trouble in hear-
ing what the speaker says, for the reason that the
pipe is continuous all the way through. This contin-
uous long pipe stands for a continuous wave. This
of course, is not a strict analogy, but may serve to
implant in the reader's mind the difference between
an interrupted spark wave and a continuous wave.
POWER IN SENDING
So far, we have only considered transmitting
generally. The question is often asked, how much
power do we need to transmit to a given distance?
This is an entirely erroneous conception for a very
40 RADIO FOR ALL
simple reason. The power used in sending has
fundamentally nothing to do with the distance. For
instance, it was demonstrated, as we stated else-
where, that a number of American amateur send-
ing stations were heard clearly in England, although
they had a power of only 1 kilowatt, which is 1000
watts. This power is equivalent to burning twenty
50-candle power incandescent Mazda lamps on a 110
volt lighting current. Certainly a very moderate
amount of power. On the other hand, the commer-
cial companies as a rule use a power which is at
least 50 times as great and often 100 to 300 times
as great. Why is this so? A few words will ex-
plain. When our receiving apparatus was very
crude, and not at all sensitive, a one-inch spark coil
could not transmit more, than one mile. In other
words, it could not be heard further than one mile
with ease in the time of the coherer, an instrument
of which we will speak later on. A few years later,
when detectors which were much more sensitive than
the coherer, came into vogue, the same one-inch
spark coil could be heard for 10 miles. Today, by
means of our super-sensitive vacuum tubes, it is
possible to hear a one-inch spark coil perhaps a
hundred miles and over. So you see the power
that we use at the transmitter has no bearing on the
distance. As a matter of fact, it can be proved
theoretically that a one-inch spark coil connected
to six dry cells, and providing we have a sufficiently
large serial, may be heard as far as it is possible to
go on this globe, which is 12,000 miles. As receiv-
ing instruments are becoming more and more re-
fined, this stage will be reached some day, because
the waves of this small one-inch coil certainly reach
that distance. The transmitting distance is simply
a matter of the sensitivity for the receiving station.
That this is not theory, is best proven by the fact
that our sending stations are becoming less and less
powerful. Years ago they were great thunder fac-
tories where a tremendous amount of power was
used. This is a thing of the past. While we still have
powerful commercial stations, their power is shrink-
ing as the years roll on. A time will come when
only an insignificant amount of power will be used
to fling messages around the globe.
THE radio receiving station is for the sole pur-
pose of receiving radio intelligence, be it radio teleg-
raphy in code or radio telephony in speech, music
or other entertainment.
It should be understood at once, before going
further, that no matter what receiving station you
have, it can receive either radio telegraphy or radio
telephony. The receiving station has the exact
counterpart in your ear. It receives any and all
sounds and noises that are floating about in the air.
So it is with the radio receiving station; with it you
can hear, if properly adjusted, any and all distur-
bances that are flung out into space by the various
transmitting stations. Of course, the radio receiv-
ing station has limitations, just the same as the hu-
man ear. To make this plain, there are many noises
and sounds that the ear cannot hear, due to its
physical limitations. For instance, sounds below
16 vibrations per second cannot be detected by the
ear. Certain animals, however, can hear these
sounds, as their hearing apparatus is tuned to low
vibrations. Going up on the scale we find that the
ear no longer responds when the vibrations go above
30,000 per second. Certain birds and insects,
however, can hear such sounds perfectly, their
Photograph by Pacific & Atlantic Photos,
President Harding delivering his address at the Arlington Cemetery on Decoration
Day. His voice was picked up by the microphones seen in front of the pulpit and
itted by radio.
Photograph by Keystone View Co.,
Here we see the huge amplifiers which were used to
receive President Harding's speech. The voice issues
with tremendous volume from these horns and can be
heard within 500 to 1,000 feet from the tower.
ears being attuned or adjusted to these vibra-
tions. The same is the case in radio ; certain waves
may be heard in a receiver while certain others may
not. When we said, therefore, that a radio receiver
can receive all messages that are floating about, we
have said so only with certain restrictions. The
radio receiver, which is just like a human ear, can
only record certain radio impulses, others cannot
record at all unless we take recourse to artificial
means, as we will learn later on. As explained in
previous chapters, receiving instruments are becom-
ing more and more sensitive for which reason we can
hear the sending station further and further away.
If we have a broadcasting station which is sending
out a band concert, and if we were to use Marconi's
first instrument, the coherer for receiving purposes,
it would not be possible for us to receive this con-
cert at all because Marconi's coherer is totally
unsuited to receive broadcasted radio music. After
Marconi's coherer came the auto coherer, a some-
what more sensitive instrument. With such an in-
strument a broadcasting station could possibly be
heard five to ten miles, but no further. Next came
the crystal detectors ; with a good one we may hear
the broadcasting station at a distance of 25 miles
or more. Still later came the audion or vacuum
tube. This instrument, being enormously more
sensitive than a crystal detector, at once increased
the range up to a thousand miles and over. Thus,
for instance, the station WJZ at Newark N". J., was
44 RADIO FOR ALL
clearly heard by receiving stations 1400 miles away.
Of course, the waves of the broadcasting station, as
we have mentioned before, go much further, only
we no longer hear them even with our present va-
cuum tube detectors. But the time is surely com-
ing when, by means of a good detecting instrument,
not as yet invented, we will be able to hear WJZ
all over the globe. We may state right here that the
range of the receiving station is mostly dependent
upon the detecting instrument, all other things be-
ing equal. The range of a receiving outfit, there-
fore, depends entirely upon the sensitivity of the
We often hear the remark made that Mr. John
Smith has a "high power" receiving station. This
is a lay expression which is totally wrong. There
is no such thing as a "high power" receiving station.
The statement should be that John Smith has an
extraordinarily sensitive receiving station.
If you have any trouble in grasping these points,
let us take recourse to another analogy. Using
a candle, which will be our transmitting station, our
eye will be the sensitive receiving station, a few feet
away. We can see the candle perfectly, as well
as the flame. Place the candle 500 feet away and
we are not aware of its presence, we just
see the flame rather indistinctly. At 1,000 feet, the
flame plus the candle has shrunk to a fine luminous
point, if we are in total darkness. Remove the
candle 10 miles from our eye and we no longer see
either the candle or the flame, although we know
perfectly well that the candle is still burning and
is sending out its light rays.
The trouble is not, therefore, with the sending
station, which is our candle in this instance, but
with our eye. In other words, our eye is no longer
a sensitive receiving detector for the light waves, al-
though we know perfectly well that the light rays
are still there. How can we prove this? By very
simple means. We attach an amplifier to our eye,
this being a telescope. If we focus this telescope
correctly upon the candle, and look through
our amplifier telescope, we again will not only see
the distant flame of the candle, but if the telescope
is a good one we will see the candle as well. Astron-
omers are making use of this very thing every day.
Millions of stars cannot be seen by the naked eye,
but the telescope brings them closer by amplifying
the stars to such an extent that they become visible
to our eye again. But the astronomer goes still
further. He knows that the eye itself is not a very
sensitive detector for light. He, therefore, substi-
tutes a photographic plate for the eye. By expos-
ing the photographic plate to the light of a star
for many hours at a time, the star is thus photo-
graphed upon the plate, which star was previously
totally invisible to the eye with the best tele-
scope. In other words we have here to do with
We make use of just such artifices in radio as
46 RADIO FOR ALL
well. For instance, a single vacuum tube is only
able to detect radio signals for a given distance.
By adding more vacuum tubes, more "stages" as we
call them in radio parlance, we step up the faint sig-
nals until finally a radio signal that could not be
heard at all with a pair of telephone receivers, and
a crystal detector, will roar out of the amplifying
horn with ear-splitting strength. We have done
in radio exactly the same thing as the astronomer
has done with his telescope. We have amplified
the radio waves while the astronomer has amplified
the light waves. Both phenomena are exactly alike
in theory as well as in practice. The analogy holds
good much further. If the astronomer has a de-
fective telescope in which the lenses are cracked or
covered by fog or moisture, we know in advance that
he will not see well. His amplification of the dis-
tant star or planet will be poor or he will see nothing
at all. It is exactly so with the radio receiving sta-
tion. If conditions are not right, for instance, if our
insulation isbad,or if the adjustments of the appara-
tus are not correct, we will hear the signals faintly,
and often not at all. Receiving radio waves, there-
fore, is not any different from receiving light waves.
If you go to the opera you would not think of using
the opera glass unless it was properly adjusted
tuned to your particular eye. You also would
not have the lenses covered with finger marks. You
know in advance that you would not see much of the
opera if you were to do that. The same thing
holds true of your receiving set. We must have
perfect insulation; all metal parts that carry the
current must make good contact all parts must be
perfectly adjusted. Only in this case will the re-
ceiving be 100 per cent., or rather approaching it,
because we have not as yet reached the stage where
we can receive 100 per cent.
We have mentioned before that radio waves pass
as readily through a stone wall as through the air.
It, therefore, does not surprise us that we can have
a modern receiving station in our library with-
out an outdoor serial at all and the waves will be
received just as well as if the outfit was stationed
on top of the roof or out in the yard. This is
true only if the detecting apparatus of the re-
ceiving outfit is very sensitive, otherwise we will
not be able to detect the waves, although they
As a general thing, it has been found in receiv-
ing that the higher up our receiving apparatus or
aerial is, the better we can receive. It also has been
found that one can receive further with a given
receiver over water than over land. Roughly
speaking, one can hear twice as well over water as
over land. To illustrate this, if we had a receiving
station anywhere near the coast, we should, with
a good crystal detector, hear a broadcasting station
25 miles inland. On the other hand, we would hear
it about 50 miles out on the sea. Scientists are not at
all certain as to the reason for this, so we will not
48 RADIO FOR ALL
dwell upon it here. Furthermore, if in a mountain-
ous country, particularly where mountains are ore-
bearing, or if we are at the bottom of a valley,
our receiving range will be cut down quite
a good deal. Such mountains make a sort of
barrier, as they do not pass the radio waves readily.
Thus, if we are in the midst of a large forest, and
our serial does not extend much beyond the tree
tops, we will often have difficulty in receiving. For-
ests cut down receiving considerably. It should be
understood that these statements are only general.
If we have a highly super-sensitive apparatus, we
can hear in a valley or a forest, although the signals
will not come in as strong as if we were out on a
plain. Steel buildings also tend to cut down the
receiving range. Thus, for instance, if a receiving
station of moderate sensitivity is located in the
heart of the New York downtown district, we will
hear practically nothing from the neighboring
broadcasting stations, unless of course the aerial ex-
tends far up above the buildings. All these facts
should be borne in mind when erecting a good re-
Another point to be remembered is that reception
during the night time as a rule is better than during
the day. The reason for this is that during the day
time the sun's rays ionize the air, which means that
the sunlight makes the air partly conductive. That
cuts down the receiving range as well. It is not a
rare occurance that distant stations are heard twice
as far during the night time as during the day.
Even now commercial stations handle most of their
traffic between sunset and sunrise because the re-
ceived signals are much more powerful during
A few words as to this greatest nuisance that
the radio man has to contend with. Static disturb-
ance is nothing but atmospheric electricity. We
are not bothered much with static in the winter time,
but during the months of May, June, July, August
and September, there is plenty of it, particularly if
we have an serial extending up into the air. Static
makes itself heard in our receivers in a sort of irreg-
ular noise that cannot be controlled today. Very
often we hear sharp clicks in our receivers which
vary up to a loud roar, particularly when a thunder
storm is approaching. Sometimes the air, even on
a perfectly clear day, is so highly charged with elec-
tricity that if we bring the lead-in from our serial,
close to the ground wire, small sparks will jump
from the serial to the ground, proving conclusively
that static electricity is collecting upon the serial.
These static noises so far have not been corrected, as
no way has been found to weed out or entirely tune
out these disturbances. Sooner or later, however,
some genius will invent a perfect static armihilator.
When he does that, his future wealth will be assured.
If you doubt that it is atmospheric electricity that
causes the racket in your receivers on a nice warm
50 RADIO FOR ALL
summer's day, you may manufacture your own
static when the air is particularly quiet by means of
your house cat. All you need to do is to stroke the
fur of "tabby," and let the fur come in contact with
the bare lead-in of your serial while you have the
receivers on your ears. You will hear exactly the
same sort of static noises if you stroke the cat the
right way, as her fur will generate static electricity.
THE earliest and perhaps the first instrument
for detecting radio waves was the coherer. This
was a rather complicated little instrument, and one
that was difficult to keep adjusted. Furthermore,
it was not at all sensitive, compared with the detect-
ing instruments of today. Fig. 17 shows the in-
Gloss tube, exhausted
strument which was composed of nothing more than
two metal plugs surrounded by a glass tube; the
small space, about one-eighth of an inch, that sepa-
rated the two plugs was taken up by nickel and
silver filings. The proportion was roughly, 90 per
cent, nickel and 10 per cent, silver. The peculiar-
ity of this instrument was that when radio waves
struck it, the filings became more conductive, and,
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therefore, passed the electrical current through bet-
ter. Further, it was possible to ring a bell with the
coherer. The simplest connection is shown in Fig.
18. Here we see the coherer attached to the asrial
and the ground, also a relay, a battery and a bell.
The instant that a radio wave impinged upon the
eerial, the bell would ring, and would continue to
ring even though the wave had passed.
In the early days, Marconi provided a sort of
tapping arrangement which, hitting the coherer,
disturbed the filings, destroying the conductibility,
and the coherer was then ready to receive an addi-
tional signal. This instrument, however, was not
very satisfactory, because it did not always respond
to radio waves, and sometimes it responded to
RECEIVING INSTRUMENTS 53
static electricity (atmospheric disturbances) as well.
This instrument, therefore, was soon discarded.
A somewhat better and simpler instrument is
shown in Fig. 19. Here are two blocks of carbon
filed to a sharp edge. On top of the carbon rests
a sewing or darning needle; the idea is that the
Carbon btock UST ll .Carbon block
needle makes a slight contact with the carbon blocks.
This was the first real detector, because unlike the
Marconi coherer, it was self-restoring, that is, it
needed no tapping to make it ready for the next
wave. In other words, dots and dashes could be
received with this detector with but little trouble.
The connection is shown in the diagram, Fig. 19 A,
and it will be noted that a battery is required with
this detector, although if adjusted exceedingly well,
such an instrument works without a battery, but
not so readily. Such a detector is quite unsatisfac-
tory for the reason that the slightest vibration, such
as footsteps in the room, disturbs the needle and
RADIO FOR ALL
makes the device inoperative until it is adjusted
again. This was one of its great draw-backs.
Soon afterwards there was developed the so-
called electrolytic detector shown in Fig. 20. It
may be considered, even today, a good detector, and
while not as sensitive as the best crystal detector
(this will be discussed later) it has the one great
advantage in that it "stays put" and does not very
easily get out of order. The electrolytic detector
has a fine platinum wire, as shown in the illustra-
tion that dips into a small cup containing a solution
of nitric acid in the proportion of about five parts
of water and one part of nitric acid. We can also use
a similar proportion of water and sulphuric acid;
both work very well. The wire which touches the
nitric acid is exceedingly fine, for which reason it
is difficult for the eye to perceive it. It is called
Wollaston wire, and is a fine platinum wire covered
with a heavy coating of silver.
When the wire is immersed in the acid, the silver
coating is eaten away by the acid and a fine plat-
Carbon cup to hold acid
inum wire remains. This wire is less than three ten
thousandths of an inch thick, so fine that it can
hardly be seen. Usually some sort of regulating
mechanism is used to make this wire dip more or
56 RADIO FOR ALL
less into the acid. As a matter of fact, the best
results are had with the Wollaston wire when it
barely touches the liquid, as is shown in Fig 21.
The wire being so extremely thin it curls over
slightly when touching the acid solution. It will
be noted that with this style of detector, as shown
in the diagram, Fig. 22, a potentiometer is
used. This potentiometer is nothing but a sort of
resistance, and is employed solely to cut down the
current from the batteries. High resistance tele-
phone receivers having a resistance of 2,000 or 3,000
ohms are used with the electrolytic detector with
good results. The potentiometer is adjusted until
the "boiling" noise is reduced to a minimum in the
telephone receivers, and the detector is now ready
to receive the signals. With the electrolytic detec-
RECEIVING INSTRUMENTS 57
tor, signals have been received over very long
The author was about the first one to introduce
the use of a carbon cup in connection with the elec-
trolytic detector, shown in Fig. 20 ; this carbon cup,
being a conductor, made a much better instrument
because metal cannot be used. Before the author's
experiments, small glass vessels having a platinum
wire fused into them were used, but these were
rather expensive. The author also found that if a
small drop of petroleum or paraffin oil was poured
upon the acid, it would keep the latter from evapo-
rating. This is quite important, as before this im-
provement was made, it was necessary to replenish
the acid almost every day. The author who had
experimented a great deal with electrolytic detec-
tors, endeavored to develop such a detector in which
no loose acids were to be used. A detector termed
the "Radioson" was designed by him, and this had
all the elements of the standard electrolytic detector.
The fine Wollaston wire was fused in a glass tube
which was immersed in the acid as shown in the
illustration, Fig. 23. The Radioson was also used
in connection with the potentiometer and high resist-
ance receivers just as was the original electrolytic
detector. Unfortunately the Radioson, once sub-
jected to strong signals or even too strong static
currents, would burn out the exceedingly fine Wol-
laston wire, after which the instrument became
inoperative. Although the Radioson was perhaps
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one of the best electrolytic detectors ever designed,
no means could be found to keep it from burning
out and the manufacture of it was given up by
Soon after the invention of the electrolytic
detector, crystal detectors came into vogue.
Dunwoody was perhaps the first man to use such a
Wollaston wire sealed
in gloss tube.
crystal, viz., carborundum. The carborundum crys-
tal is a green-bottle colored sharp crystal, which
is a manufactured product. Carborundum is used
mainly as an abrasive, being harder than glass, which
it scratches easily. The carborundum detector is
shown in Pig. 24. The connection is similar to
that of the electrolytic detector and is, therefore,
not shown here. As will be seen the carborundum
crystal is clamped between steel needles under a
certain amount of pressure, in such a way that the
needles rest against the surface of the crystal. The
amount of pressure that the needles bear against
the crystal is determined by experiment until the
signals come in loudest. The amount of pressure
varies for every crystal, and must be found by trial.
Once adjusted, the carborundum detector needs no
attention, and it will not get out of order readily.
Jars do not affect it, and for that reason it has been
used to a great extent on board ships, in portable
outfits, etc. Unfortunately, this detector is not
very sensitive. As a matter of fact, it is not as
sensitive as the electrolytic detector, but where sta-
bility is required this detector is excellent.
Fig. 25 shows one of the best of the early detec-
tors, viz., the silicon detector. Silicon is a manu-
factured substance, which is a by-product of the
electric oven in the manufacture of abrasives ; it is
a cousin to carborundum. Silicon is a hard rock-
like substance of a dark silver-gray color. The de-
tector is shown complete in Fig. 25. A small piece
60 RADIO FOR ALL
of silicon broken from a larger piece by means of a
hammer or in a vice, about a /4 inch by *4 inch,
is first imbedded into a soft solder, as shown
in the separate illustration of Fig. 25. The idea of
this pellet is that contact is made on five sides with
the metal, which is simply cast around the silicon,
and the crystal part of this round pellet is after-
Blunt brass point
wards placed in contact with the contact mem-
ber, as shown in the illustration. The contact mem-
ber is nothing but a piece of brass, which is not very
sharp at the end, but rather blunt. The amount
of pressure upon the pellet is varied by a spring.
In detectors of this kind, not every point of the
silicon is equally sensitive. Some points are very
sensitive while others are not. Some of the sensi-
tive points require more pressure than others. All
tnis is found out by experiments. The silicon de-
tector is quite sensitive, and probably is as good a
detector as the electrolytic type, with the great
RECEIVING INSTRUMENTS 61
advantage that it requires no battery. This was
the first detector invented that required no battery
whatsoever to detect radio signals, and for that rea-
son it is a favorite instrument with the experimenter.
The silicon detector has also the great advantage
in that it is not easily "knocked out," as most other
detectors are. It is not so sensitive to static elec-
tricity and does not burn out easily. When con-
nected, as in Fig. 26, a set of receivers of at least
1,000 ohms should be used for best results. We
might state here that a 75-ohm receiver, such as is
used in house phones, should never be used in con-
nection with radio waves. The results are very poor.
For short distances a 75-ohm receiver may be
used, but even then it is not sensitive and not
Soon after the silicon detector was invented,
62 RADIO FOR ALL
Greenleaf W. Pickard, the inventor of the silicon
detector, invented a host of other detectors, all of
which use a native mineral crystal, such as, for in-
stance, iron pyrite, copper pyrite, bornite, etc. All
of these detectors are used similarly to the silicon
detector, the crystal being cast into a soft metal in
pellet form. This pellet is used in the same way as
the silicon detector; sometimes a sharp brass con-
tact point is used with some minerals and at other
times a fine wire is used, which latter is termed a
Cattvhisker. Such a detector is shown in Fig. 27.
This detector uses as a sensitive member the mineral
or crystal known in the trade as Radiocite. Radio-
cite is a treated iron pyrite and is as shiny as polished
gold. A good piece of radiocite is equally sensitive
over its entire surface. It is probably as sensitive
as any of the mineral detectors in use today. As
with all other crystal detectors, no battery is used
RECEIVING INSTRUMENTS 63
in connection with it. In the radiocite detector no
sharp point is used, but rather a fine gold wire cat-
whisker. A catwhisker is a piece of fine wire about
No. 26 or No. 28 B & S gauge phosphor bronze. This
is attached as a rule to some sort of handle or other
adjusting means so that the pressure of the wire
upon the surface of the mineral may be varied. If
one spot burns out or becomes inoperative, a new
point is found by experiment.
One of the most sensitive and most widely used
detectors is made of Galena, a lead ore of which
there are different grades. It is known under many
trade names as well. A good piece of galena is
probably as sensitive as any crystal yet discovered,
but it is not stable. A catwhisker, as explained
under the radiocite detector, is used with the galena
crystal and the amount of pressure has to be found
by experiment. Ordinary galena is not sensitive
on every spot, but there are certain grades which
are equally sensitive over the entire surface; this
is known as Argentiferous Galena, which means
that it is silver bearing. On the other hand not all
argentiferous galena is equally sensitive, and there
is no hard and fast rule about it. It must be found
by experiment. The connection for the radiocite, as
well as galena detector, Fig. 28, is the same as shown
in Fig. 26. No battery is used with galena, and as
a matter of fact a battery will destroy the usefulness
of it by burning out the sensitive points. With
galena, a fine brass wire No. 24 or No. 26 B & S
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gauge is used ; a stiff gold wire of the same dimen-
sion may also be used, as it is non-oxidizing. It may
be stated here that most any metal wire can be used ;
they all work equally well with the possible excep-
tion of iron, which soon becomes coated with rust
and will then no longer operate.
All crystals are only sensitive if absolutely clean,
and their usefulness becomes destroyed immediately
upon being handled with the bare fingers. The
natural oil of the hands tends to destroy the sensi-
tiveness as the crystal surface becomes coated with
it. The best method to employ with all crystals
is to clean them frequently with a piece of absorb-
ent cotton moistened with carbon tetrachloride.
This high-sounding name is nothing but Carbona,
which may be purchased anywhere. There are
some liquids advertised under high-sounding names,
all of which are in reality Carbona; this does the
work 100 per cent, well, and should always be used
where crystals are employed. After rubbing the
crystal with the moistened cotton, it should be left
Brass or copper
for a few minutes until the liquid has evaporated.
The crystal will then be found in first class
Although we have stated a little further back
that most crystal detectors have the sensitive mineral
embedded in a metal pellet, the amateur or experi-
66 RADIO FOR ALL
menter does not always require this, and Fig. 29
shows several simple home-made detectors. The
illustrations are so self-explanatory, that no further
details need be given. Base boards may be of wood,
hard rubber or any good insulator. As will be seen
in these illustrations, the detector mineral is clamped
by simple holding devices; anything that will hold
the crystal down so that it will not move, and at the
same time make good contact with it, may be used.
The catwhisker wire is best (a No. 24 or No. 26
B & S brass gauge), or phosphor bronze wire. It
may be straight, or coiled in pig-tail fashion, either
will work equally well. The clever experimenter
can change the design to suit his own individual
tastes, and the chances are that the device will work
well. The trouble with most mineral detectors is
that their adjustment does not keep for any length
of time. Jars, or static surges in the serial will
cause the detector to become inoperative, after which
it must again be adjusted. The better the crystal
and the more sensitive spots it has over the entire
surface, the easier the adjustment will be.
We now come to a vastly different sort of de-
tector, namely the Audion, or as it is commonly
called, the "Vacuum Tube." This detector works
upon an entirely different principle from any of the
former ones described, and is in general use today
for reasons which we shall learn presently. The
audion makes use of a principle first discovered by
Edison, and for that reason termed the "Edison
Effect." Edison found that if he placed two fila-
ments in an ordinary electric lamp instead of one
filament, and lit them both, a current would flow
across the vacuum or empty space. It is this prin-
ciple that is now being used in the vacuum tube.
Fig. 30 shows a standard vacuum tube where we
have the filament, which is the same as that used
X Tube with
\ plate re-
in an incandescent lamp; this is heated by means
of a battery of from four to six volts. We next
have the grid which may be in the form of a grid-
iron or a spiral, it making little difference which.
Opposite the filament and with the grid in the mid-
dle, we find the plate, usually a small piece of nickel
or other metal. The connection of the simplest
audion is shown in Fig. 31. If we make the plate
positive with respect to the filament, we find that
highly charged electrical particles called "electrons"
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travel constantly from the filament to the cold plate.
It was soon found that the vacuum tube acted as a
sort of valve for the electrical current, allowing
the high frequency currents as they came over the
serial to travel in one direction in a vacuum, tube
but not in the other. In this respect the vacuum
tube is the same as a crystal detector, which also
acts as a valve, permitting currents to pass one
The vacuum tube was first invented by Dr.
Fleming, to whom belongs the honor of using it
first as a detector for radio. He was using only
a two-element tube, viz., an exhausted bulb contain-
ing a filament and a plate. Dr. De Forest
conceived the idea of introducing a third elec-
trode into the tube, as explained above. The
purpose of this electrode which he called the grid,
serves only to control the flow of the electrons at-
RECEIVING INSTRUMENTS 69
tracted by the cold plate. It is the grid that makes
the vacuum tube the exceedingly sensitive apparatus
that it is. Making the grid alternately positive and
then negative varies the amount of current that
flows from the hot filament to the plate, decreasing,
and even stopping it entirely. The grid simply acts
as a gate valve which controls the plate current.
The curious thing about the grid is that it uses no
great amount of power. A modern vacuum tube
is exhausted to a very high degree, because it was
found that unless the vacuum was perfect, the sensi-
tivity of the tube was very poor. It is not neces-
sary here to go into a very technical discussion of
the vacuum tube, as we are merely interested in its
functioning. The study of the vacuum tube, how-
ever, is a science in itself today, and for that reason
it can only be treated generally here. We must,
however, add that the vacuum tube is far more sen-
sitive than other detectors, particularly when used
in connection with other vacuum tubes. It was
found, for instance, that this was the case when
several tubes were coupled together; this gives us
the so-called two-step or three-step amplifier, which
will be discussed later on. The idea of these ampli-
fiers is for each to step up the exceedingly weak
current received from the first tube, usually called
the detector tube. By means of such a stepping
up process, it is possible to bring in signals over
tremendous ranges, a thing impossible to do with
any other detector known at this time.
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We have seen in previous chapters that each
radio wave-length is dependent upon the length of
wire of each aerial. If it were possible to make all
serials of exactly the same length and capacity, and
if all stations were transmitting at exactly the same
wave-length, we would not need any tuning devices.
Unfortunately this is not the case. When we install
an serial, we cannot always make it of the length or
capacity which we desire, but are hampered by phys-
ical and geographical limitations. In other words,
our serial is usually a compromise. On the other
hand, the various transmitting stations all send on
different wave lengths, and for that reason, many
different tuning devices are used. One of these,
and the oldest, is the Tuning Coil, shown in Fig. 32.
This is nothing but an aerial wound upon a cardboard
tube or other circular or square piece of insulating
material. The tuning coil is simply an extension
of the serial. Even though we have an aerial which
is only 100 feet long, by attaching more wire to it
in the form of the tuning coil, we thereby lengthen
the serial. The tuning coil, as shown in the illustra-
tion, is simply an insulated wire wrapped upon a
cardboard tube, its size is immaterial. Tuning
coils may be made in almost any size, from the small-
est one wound upon a pencil, to the largest, as
big as a barrel. The more wire we use, the more
wave-length our tuning coil will be able to absorb,
so to speak. Of course, in practice tuning coils
are built for a certain capacity, all depending upon
what it is to be used for. If, for instance, we have
but a little serial and wish to receive from stations
having a wave length of say 650 meters, a small
coil about 6 inches long and 2 inches in diameter and
wound with No. 24 B & S gauge wire will do nicely.
The purpose of the slider is simply to add more or
less wire to the serial; it is but an adjustment the
72 RADIO FOR ALL
same as, for instance, a rubber elastic that you
stretch more or less to make it longer or
shorter as you desired. It goes without saying that
the slider of the tuning coil must touch the wire,
as otherwise no connection would be made. In Fig.
33, we show the simplest connection for a tuning
coil. This, as will be seen, duplicates the connection
of the crystal detector. We have here merely add-
ed the tuning coil in order to tune the circuit. By
means of this tuning coil, it now becomes possible
to tune out unwanted stations merely by moving the
slider back and forth and so connecting more or less
wire to the aerial. For instance, if two stations are
sending at the same time, by moving the slider back-
ward and forward it becomes possible to tune in or
out the unwanted station, and listen only to the one
we desire to hear. In Fig. 34, we show the same
tuning coil, but with sliders. The two sliders are
somewhat of an improvement, for the reason that
RECEIVING INSTRUMENTS 73
better tuning is accomplished with them. This is
what is technically called a more balanced circuit.
It is possible to still add more sliders to one tuning
coil. Years ago, three-slider tuners were in vogue,
but they are now no longer the fashion.
The Loose Coupler is another form of tuning
coil and this instrument, which was formerly used a
great deal more than at the present time, is really
one of the best tuning devices known. Instead of
using just one coil, as for instance the tuning coil
just described, a loose coupler uses two coils one
sliding into the other without touching. The
loose coupler is an electrical transformer, as it has
been found that if a radio current traversed one coil,
another tuning coil standing close by would be af-
fected, although no wire touched the first coil. This
is termed an "inductive effect." In other words,
the energy is radiated from one coil to another, the
same as a stove radiates heat to objects that are
close to it.
As we just mentioned, the loose coupler is a
transformer. The current that comes in over the
terial in the form of radio waves is a high frequency
current. By that we mean that waves swing back
and forth very rapidly. It is the purpose of the
loose coupler to change this energy into a more
suitable form. We again take recourse to an anal-
ogy. In Fig. 36 we show, by means of a lever ac-
tion, the principle of the transformer. We are all
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familiar with the lever action whereby a man who
weighs only 150 Ibs. can raise a weight of 1000 Ibs.
by means of the lever. Is he getting something for
nothing in this case? Certainly not! You cannot
get free energy, but the experiment in Fig. 36 sim-
ply shows that force plus time may be transformed
into something else. In this case the man who
weighs 150 Ibs. is the force and the time is the inter-
val that it takes him to reach from point A to point
B. The two added together are sufficient to raise
the 1000 Ib. weight, the distance from C to D. The
longer the lever arm L, the more weight we can
raise. Archimedes told us that "give him a long
enough lever he could raise the earth from its
hinges." Always providing that he has a sufficiently
long lever and a fulcrum, or point of rest which is
shown at F in Fig. 36. Summing up, we understand
now that by means of a small weight we are able to
lift a much heavier one.
This analogy holds with our loose coupler, which
we have shown in Fig. 35. The loose coupler has
two coils; the primary, which is usually the outer
tube, is always wound with a coarser wire, while
the inner tube is wound with a finer wire. As in the
tuning coil we have a slider upon the primary, or
if we do not use a slider we may have taps (connec-
tions) taken at every few turns of wire, if we so
desire. On the secondary also, we may have a
slider or taps brought out, both of which are the
same. The inner tube is made to slide back and
forth upon sliding rods so that the degree of coup-
ling, as we call it, may be changed. If the inner
tube, called the secondary, is pushed into the outer
tube, which we call the primary, we have a complete
electrical lever system, as shown in our analogy Fig.
36. The energy that comes into the primary is now
76 RADIO FOR ALL
raised exactly as the weight is raised by means of
a lever, and we get a marked effect from the second-
ary. The more we pull out the secondary tube,
the less our lever action becomes. It is as if the
man in Fig. 36 were to move down to the point F
where it would become impossible for him to raise
the weight at all, or even to budge it. By using
the loose coupler, we do not get something for noth-
ing any more than if we raise a stone by means of
a lever. In both cases we perform work. In our
loose coupler, the result as a rule is that we get
louder and better signals.
Reverting back to Fig. 35, the tubes of the tun-
ing coil may be of cardboard, hard rubber or com-
position, or any good insulating material. No steel
or iron should be used in the construction of a good
loose coupler. Its size is immaterial providing the
proportions are right, this being determined by ex-
periment. The important part is that the second-
ary must come as close as possible to the primary.
In other words, the diameter of the two tubes must
be so that the secondary tube, when moved inside the
primary will take up the entire air space without,
however, touching the outer tube. The closer the two
windings come together, the better it is. In Fig. 37,
we show the simplest connection for a loose coupler,
crystal detector and phones. Very good results are
had with this circuit, and the loose coupler is partic-
ularly efficient for tuning out interference to a cer-
tain degree. It gives what is called sharp tuning,
because if two stations operate at a close wave
length, let us say one at 360 meters and another
at 320 meters, the loose coupler will give very good
results by reason of its sharp tuning. In this case,
it will be possible to tune in either station, if in
connection with the loose coupler we use an addi-
tional instrument, namely the condenser, which we
will describe presently. When the connections are
made, as shown in Fig. 37, we must keep the second-
ary all the way in, and then adjust the slider on the
primary until we hear the signals well. We now
slide the secondary in and out, more or less, and in
doing so, we move the slider upon the secondary also,
until we reach a point where signals are loudest.
This point is different for every station to which
we are listening.
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Variometers, Fig. 38, are usually built by having
one spherical winding rotating within another spher-
ical winding, as shown in the illustration. Both, how-
ever, are wound with the same wire. By moving the
inside, which is called the rotor, the inductive effect
between this and the other winding, which is called
the stator, is changed. It acts exactly as a loose
coupler, but is somewhat less complicated. It is,
however, not used much in connection with crystal
detectors, but rather with vacuum tubes where a fine
balance is necessary. The same is the case with the
Vario-coupler shown in Fig. 39, which is also used
almost exclusively in connection with vacuum tubes.
In this instrumentwe have an outer tube wound with
a heavy wire, while the inner tube which rotates
upon its axis is wound with a finer wire.
In a radio circuit, in order to do fine tuning,
we must often take recourse to the condenser which
instrument is used to do just what its name implies,
viz., condensing the electric current. This is per-
haps not exactly accurate, for there is no condensing
done in radio work, but rather a storing up
Consider Fig. 40. Here we have a spring which
we compress by means of a weight. As soon as we
take the weight away, the spring returns to its orig-
inal position. What have we done? We have
80 JRADIO FOR ALL
simply stored energy into the spring. The elec-
trical condenser is used in exactly the same way,
viz., to store electrical energy. However, that is
not its only purpose. Just as the spring may be
used for other purposes besides that of storing me-
chanical energy, so the electrical condenser may be
used for other purposes also.
A condenser is a capacity or a vessel in which
electrical energy is stored. The simplest form of
electrical condenser is shown in Fig. 41, where we
have a metal plate A, a glass plate B, and another
metal plate C. By means of this arrangement, we
may store electrical energy upon the inside surfaces,
on plates A and C. The larger we make the metal
plates, the more electrical energy may be stored.
The form shown in Fig. 41, is used in many con-
densers today. The metal plates A and C may be
any form of metal, such as, for instance, tin or metal
foil, while the glass plate B may be replaced by a
piece of paraffin paper. In other words, any good
metallic conductors may be used if coupled with
a good insulator. The better the insulator, the bet-
ter the condenser will be and the greater its elec-
trical capacity. In the commercial condensers,
paraffin paper, varnished silk, sulphur, sealing com-
pounds, or best of all, mica, is usually used. In
Fig. 42, is shown a simple condenser; this is also
shown opened up in Fig. 43. It is made by rolling
together two strips of tinfoil between several strips
of paraffin paper. The whole, when rolled together
and assembled, becomes the condenser shown in Fig.
42. By rolling it together, it takes up less room.
This type of fixed condenser, as it is termed, is
generally used to connect across the telephone re-
ceivers; this will be described in a later chapter.
The purpose of this little condenser is to store up
82 RADIO FOR ALL
the electrical current and then discharge that cur-
rent into the telephone receivers when the condenser
becomes full, so to speak. If you will refer to our
spring analogy you will readily understand the
principle, and how it operates. In radio work,
where fine regulation is required, we make use of
still another condenser, as shown in Fig. 44. This
condenser, instead of being fixed, is variable. As
will DC seen, there are a number of plates which are
usually made of zinc or aluminum, which mesh into
each other to a more or less degree. The more
plates we have and the closer they come to each
other, the higher will be the capacity of that conden-
ser. For certain purposes we need only a small
condenser of a few plates, while in others we need a
larger one of a great many plates. It is just like hav-
ing a small spring and still another very large one.
Both have their uses, and both are very necessary, all
depending upon what work they are required to do.
In Fig. 45, we show the simplest elementary con-
RECEIVING INSTRUMENTS 83
nection, where we have a crystal detector, a tuning
coil without a slider, a pair of phones and a tele-
phone condenser. This is a peculiar connection
because in it we wish to show that we can tune by
means of the condenser. As will be seen in this
tuning coil, we do not use any slider by which the
length of the serial may be changed, which would
/- Waxed paper strips
\ AL. '.- . __
thus change the wave length. This is performed
entirely by the variable condenser. When we ad-
just the latter, we also change the relation of the
tuning coil, and in fact we are changing the wave
length until a point is found where the signals come
in best. This is a finely balanced circuit, and the
amount of wire on the little tuning coil should be
in direct relation to the condenser. In other words,
if there is too much wire on the tuning coil and the
capacity of the condenser is small, we cannot do
much tuning. For the best results, as for instance
for receiving broadcast music on a wave length of
360 meters, we could use a small coil, one inch in
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diameter, wound with about 70 or 80 turns of No.
18 enamel wire, while the condenser should be of
the commercial variety known as a 23-plate conden-
ser. Then, all we have to do is simply adjust the
condenser until the signals are heard best.
In this illustration, we also see where the phone
condenser is located. This phone condenser stores
the energy of the circuit, and discharges it into the
telephone receivers which enables us to hear the
signal more loudly.
The two forms of condensers shown here are of
course not the only ones, as many more types of
RECEIVING INSTRUMENTS 85
either fixed or variable condensers are made. How-
ever, all of them are practically the same, roughly
speaking, and so it is not necessary to enlarge
upon the subject which is now well understood by
VACUUM TUBE ACCESSORIES
We have learned something about the vacuum
tube which was described previously in this article,
and in Fig. 31 we have shown the simplest connec-
tion of an audion detector. There are, however, a
number of other auxiliary instruments used in va-
cuum tube systems which give certain refinements.
The vacuum tube, when it is used singly, acts as
a detector and detects the signals the same as a crys-
tal detector. Also, we might state here, that the
crystal detector is a better rectifier "valve" than
the vacuum tube. The vacuum tube itself
only becomes of great importance when used
in special circuits.
With a crystal detector, or in the ordinary sin-
gle vacuum tube circuit, the incoming signals act
upon the phones and we hear the signals with a cer-
tain strength. Let us now consider the vacuum
tube and the incoming signal. We may indeed,
by certain means, boost up the very weakest of sig-
nals and amplify or magnify it a hundred or a thou-
sand or a million times its original strength. It is
just as if you take a piece of film such as is used
in a moving picture theatre and examine it with
your eye. The figures are so small that you can
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hardly distinguish them. The regular film which is
about the size of a postage stamp here stands in our
analogy as a single vacuum tube. We can, how-
ever, take that film, and by using a powerful light
enlarge the little picture (no larger than a postage
stamp,) by projecting it upon the screen. We
thereby amplify or magnify the original picture
several thousand times. We can amplify or en-
RECEIVING INSTRUMENTS 87
large it a million times if necessary, all depending
upon the amount of light we put behind a film and
the distance from the screen. This is graphically
shown in Fig. 46.
We may do precisely the same thing with a va-
cuum tube, but we must use additional energy, the
same as in our film where we use energy (the elec-
, I k ftR*tf AMPLIF1EDT
(B BATTERY) ^AYE; WAVE J
trie current which produces the light) to project
the film upon the screen. In other words, we can
take the detector tube and enlarge the original small
and weak signal, and boost it up until the sounds
come out loud from a loud speaking horn, which
in our analogy stands for the moving picture screen.
The electrical connections for a vacuum tube ampli-
fier are shown in Fig. 47. This is what is called
technically a two-step amplifier. We show this
connection simply because without it, it is almost
impossible to bring home the meaning of the va-
cuum tube auxiliary instruments with which the
reader is as yet unfamiliar. In this circuit we have,
as before, the serial, the ground, the variable conden-
ser, the blocking or phone condenser and several
88 RADIO FOR ALL
other instruments as well. We find, for instance,
that several transformers are used, viz., what is tech-
nically called the Audio Frequency Transformer.
AUDIO FREQUENCY TRANSFORMER
This transformer, Fig. 48, consists of just an
iron core upon which is first wound a coarse wire
termed the primary, and on top of this a finer wire
A- Variable condenser; B-Gnd leaKand condenser; C-Vario-couplen
D- Detector tube; E- Amplifying transformer; F-Amplify/ng tube;
G- Rheostat; H- Storage battery; J-B" batteries; K- Receivers;
termed the secondary. The ratio of these trans-
formers is usually such that, electrically speaking,
the value of the secondary is about ten times as
much as that of the primary. The audio frequency
transformer is in principle the same as the loose
coupler, which we studied before, and the purpose
of the audio frequency transformer is to transform
the energy from a low level to a high one. The
purpose of this transformer, as shown in Fig.
47, is to boost up the weakest signals, trans-
forming them into stronger ones. The trans-
former by itself could never accomplish this, and
in order to make the lever action work perfectly,
we take recourse to a battery which is connected to
the transformer and with the vacuum tube, as shown.
By means of this additional electrical energy we are
now in a position to boost up and relay the weak
Iron core s Primary
signal. In this connection, we have shown first a
detector tube, while the other tubes are amplifier
tubes. By this we mean that the first tube receives
the signal, while the other tubes are merely used as
pumps to boost up the electrical energy until the
signal finally comes from the phones so loudly that
if we connect the phones with an ordinary sounding
horn, loud signals or music will issue from the horn.
The battery used in this case is a so-called "B" bat-
90 RADIO FOR ALL
tery, or high voltage battery which has been found
necessary to aid in boosting up the weak signals. As
a rule batteries anywhere from 24 to 300 volts are
used, all depending upon the circuits and the pur-
pose for which they are used to boost up the
It should be understood that the audio frequency
transformer is used only to boost up the weak sig-
nal as it leaves the first detector tube. It is not
in the province of this transformer to do anything
save amplify the signal which is detected by the
detector tube. In other words, if outside inter-
ference or static comes over the serial, the trans-
former amplifies these noises as well. This trans-
former, therefore, acts only as a sort of pump in-
creasing the pressure, but it has no control over
the flow that is pumped to the next tube. We shall
see further where another sort of transformer may
be used to obviate some of these difficulties.
In Fig. 47, we also find another new instrument,
the Rheostat, shown in detail in Fig. 49. This is
simply an electrical resistance and is used solely to
increase or decrease the glowing of the vacuum tube
filament. When signals are received, it has been
found that the filament must glow at a certain in-
tensity. Some signals come in best when the fila-
ment is burning very brightly, while with other tubes
the signals come in best when the filament is only of
a cherry red. This depends upon the make of the
RECEIVING INSTRUMENTS 91
tube and the vacuum of the tube itself. The rheo-
stat is, therefore, simply an accessory to regulate
the filament's incandescence.
In Fig. 47 we have another newcomer, which
is termed the Grid Leak, and its condenser. It has
been found that when the grid condenser is used,
stance wire wound on fiber strip
as shown in the illustration the signals will come
in about twice as well as if none was used. How-
ever, this condenser alone would not be sufficient,
for the reason that the accumulation of electrons,
which are highly charged electrical particles on the
grid of the vacuum tube, would interfere with the
normal working of the tube. We must provide
a means to let the surplus electrons leak out without,
however, letting them out too quickly. It is as
if we had a boiler under which a constant fire was
maintained. In order to provide a remedy, we in-
92 RADIO FOR ALL
stall a safety valve. This valve is used for the pur-
pose of giving off the surplus steam and so keep the
boiler free from harm. It is the same with the va-
cuum tube. While of course, the vacuum tube
would not burst, even if we did not use the grid
leak, electrically speaking, the tube would not func-
tion properly. Hence, the grid leak, which is a sort
of safety valve to let the surplus accumulation of
electrons run off. The grid leak is nothing but a
very high resistance, sometimes millions of ohms
high. It may consist of only pencil lines drawn
across a piece of stiff Bristol board; These pencil
line are but slight electrical conductors, but the re-
sistance is enormous. It suffices, however, to allow
the surplus electrons to leak off. There are various
ways and means to make grid leaks, and a popular
form is shown in Fig. 50. Here we have a piece
of cardboard or fibre upon which is traced a fine
line in India ink. This line acts the same as a pencil
line. The whole is enclosed in a tube to prevent
moisture or dust from settling upon the grid leak.
Connections are made on the ends by metal clips.
Fig. 51 shows a grid leak and condenser combined
as two instruments, which are usually used in con-
junction. The grid leak condenser is small and is
similar to a telephone blocking condenser, and the
grid leak is traced by means of China ink upon a
piece of fibre ; the whole is enclosed in waxed paper.
Assembled Grid LeaK
India inK or
Method of Assembling
RADIO FREQUENCY TRANSFORMER
In Fig. 47 we have learned all about the audio
frequency transformer. We know that this trans-
former amplifies static and also other disturbances,
as well as the signals. For that reason it is not
possible to use many such transformers, or, techni-
cally termed, many steps of audio amplification. If
we use more than three such transformers and their
respective vacuum tubes, additional noises are all
RADIO FOR ALL
RECEIVING INSTRUMENTS 95
amplified, and the amount of noise which we get in
the phones is tremendous. For that reason, we take
recourse to what is termed a Radio Frequency
Transformer, which is shown in the hook-up, Fig.
52. The radio frequency transformer may consist
of only two windings, one adjacent to the other on
a cardboard tube. The simplest form is shown in
Fig. 53. The wire used on this is usually exceed-
ingly fine, No. 40 B & S wire, or even thinner. The
two windings act upon each other by induction,
and do not make connections physically. In Fig.
52, the first tube is an amplifier, and this amplifies
the weak signals as they are coming in over an asrial.
The radio frequency transformer steps up these
96 RADIO FOR ALL
weak signals, amplifying them and passing them on
to the detector tube. We now get the net result,
with the detector tube in a position to detect already
fairly strong signals which may then be amplified in
the audio frequency amplifiers, and boosted up
further by a second or a third transformer, if so
desired. We do not necessarily stop here because
we may use more than one radio frequency trans-
former; we may use two or even more. As this,
however, brings us into higher technicalities, we will
not go further, beyond showing the principle so that
the reader may grasp the difference between the two
kinds of transformers.
To resume, and in a few words, we may say that
the radio frequency transformer boosts up the very
weak radio frequency currents so that the detector
gives maximum results, whereas the audio fre-
quency boosts up the audible signals. The radio
frequency transformers, in other words, amplify sig-
nals that would be lost otherwise, while the audio
frequency transformers give volume to signals
which are already audible.
In order to receive signals or broadcasted enter-
tainment by ear, we use a telephone receiver, of
which two simple types are shown in Fig. 54 ; this
consists of the following: First we have a power-
ful magnet which attracts to it a thin iron dia-
phragm. This diaphragm is clamped tight like a
drum head along its outer edge. Upon the magnet
are mounted two pole pieces around which are
wound many thousand turns of exceedingly fine
wire, almost as fine as the human hair.
Ordinarily when no current is sent into the tele-
phone receiver, the diaphragm is pulled down some-
what to the pole pieces, although it must never touch
them. If it does, no sound will be received. If,
however, a weak electrical current passes through
these spools, the diaphragm will either be pulled
down more if the current is in the right direction,
or if the current is in the wrong direction, it will
weaken the magnetism on the pole pieces. In this
case, the diaphragm is not attracted. These little
variations make the diaphragm vibrate more or less.
These vibrations are passed on to the air, and the
air vibrating in unison with the diaphragm is
changed into sound waves, which are sent on to our
ear, where we hear them. A telephone receiver is
a marvelously sensitive instrument, and it is possi-
ble with it to detect currents of less than one mil-
98 RADIO FOR ALL
lionth of an ampere and less than one hundred thous-
andth of a volt. It is, therefore, an ideal instru-
ment to detect the weak radio signals as they come
over the serial.
In radio we usually use two such receivers, which
as a rule are provided with a head piece or
head gear; this is slipped over the head, pressing
the two receivers against the ears. It has been
found that two receivers are better, because no out-
side noises reach the one ear, as would be the case
if one receiver only was used.
Receivers for radio purposes should be wound at
least to 1,000 ohms, or better to 2,000 ohms, and for
certain other purposes to 3,000 ohms and higher.
Telephones wound to 75 ohms such as the usual re-
ceiver used on our house telephones are of no value
for radio. Their resistance is not high enough, not
even in connection with a crystal receiver.
A good head set should give an audible click in
the ears, if the two cord tips at the end of the cord
are tapped upon the tongue.
In Fig. 55 is shown a Tone Amplifier or loud
speaker known by its trade name as the Magnavox.
This loud speaker works upon a principle where a
small coil, through which the received current flows,
is influenced by a powerful electro-magnet. It is
another case of boosting up the sound which is re-
ceived from the last amplifier tube. Such tone am-
plifiers can throw the voice or music over distances
100 RADIO FOR ALL
of one-half mile and more, and if a person stands
in front of one of these giant horns, the amount of
sound that issues from it is simply terrific. Of
course, not all tone amplifiers work so loudly. Those
made for home or parlor purposes do not use so
much current, and therefore do not give so much
power. There are a number of types of tone ampli-
fiers, but most of them work along the same electro-
magnetic lines, and if they do not use the outside
battery in order to create a strong electro-magnetic
field, they either use strong magnets to accomplish
the same result, or necessitate the use of a very high
tension battery in the amplifier. Such tone ampli-
fiers are nothing but transformers or relays, trans-
forming or relaying a weak sound into a loud one.
As a matter of fact, most tone amplifiers rely upon
acoustic means as well, all of them requiring some
sort of horn, without which only mediocre results
are achieved. The horn itself, is an acoustic ampli-
fier, as anyone knows who has ever talked through
a megaphone. Due to the echoes set up inside the
walls of the horn, the sound is thus amplified.
IN former chapters we learned something about
tuning ; this is nothing but resonance. We all know
the experiment of standing near the piano and sing-
ing a certain note into it ; when we reach the correct
or fundamental note, the piano begins to sound that
particular note in sympathy. We may then say
that we are in tune with that particular string which
sounds in our ears. Likewise in radio, we make
use of a similar system, except that we use electrical
tuning instead of acoustical tuning. Tuning con-
sists as a rule in merely attuning our serial electri-
cally to the same length as the aerial that is trans-
mitting to us. In other words if a broadcasting
station is transmitting on a wave of 360 meters,
we must attune our aerial to the same wave,
namely, 360 meters. If we have an aerial which
is 260 meters long, electrically speaking, it
stands to reason that we must add 100 meters
to this aerial in order to receive the wave at all. We
have learned in other chapters how this may be ac-
complished. If we have a receiving outfit, all we
have to do is move the slider of our tuning coil back-
ward and forward until the signals come in at maxi-
mum strength. When that point is reached, we
know that our aerial, electrically speaking, must be
RADIO FOR ALL
360 meters long. We have also seen in Fig. 45 that
we need not have sliders on the tuning coil in order
to tune. We may use a condenser for tuning pur-
poses because its electrical equivalent is the same
as a tuning coil slider. By adding more or less
capacity to the condenser and therefore to the tuning
coil, we change the electrical value of the tuning
coil, and also its wave length. This is not literally
true, technically speaking, but we must use this lan-
guage to bring home the meaning.
We therefore learn that we may tune either by
lengthening the serial with additional wire, or by
using a capacity or condenser in connection with a
wire coil. Both, if correctly apportioned, give the
same results. Before we can receive signals, or am-
plify them, it is of the greatest importance that we
tune in to the right wave length. An aerial must be
in electrical sympathy with the sending station be-
fore we may hope to receive signals. In Figs. 56
and 57, we have shown the elemental methods of
tuning. Of course, there are many other ways of
tuning, all of which, however, are along the same
principles as those just enumerated. For instance,
we have seen where we tune with a loose coupler.
This, however, is exactly the same as if we were
tuning with a tuning coil. As a matter of fact, as
we mentioned in the previous chapter, referring to
the loose coupler, this latter instrument is nothing
but two tuning coils, one sliding into the other. In
the variometer, also, we have a sort of loose coupler
with which the tuning is accomplished by changing
the inductive relation between the two coils. This
acts similarly to the tuning coil slider because the
two coils either assist or else buck each other. Elec-
104 RADIO FOR ALL
trically speaking, therefore, the variometer or the
variocoupler, either add wave length to the serial or
subtract wave length from the serial. This is only
figuratively speaking and mentioned here in order
to drive home the point to the reader.
In a vacuum tube set, many people think that
when they adjust their detector tubes, their ampli-
fier tubes or their rheostats, they are tuning in.
This is erroneous because there is no tuning done in
these instruments at all. We have learned that
amplifying tubes simply belong in a pumping sys-
tem which does not do any tuning at all, but simply
amplifies the signals already received and tuned.
It should, therefore, be remembered by the reader
that tuning is only done directly in the serial system,
never in the outside circuit. Of course, it goes with-
out saying that there are circuits which are balanced
in such a way that they are again influenced by the
tuning, and vice versa. Therefore, if the two cir-
cuits are out of balance, both must be adjusted in
such a way that fine tuning becomes possible.
Perhaps an analogy in tuning will not be amiss
here, and we have a particular analogy that covers
tuning nicely. Take the musical instrument, the
trombone shown in Fig. 58. You all have seen this
instrument, as nearly every orchestra boasts of one
or more. It is known by all of us that while the
musician blows into the mouth piece, he varies the
length of the trombone by moving the sliding mem-
ber back and forth. If he wants to get a deep note,
he pulls the sliding member almost all the way out,
and this gives him a long sound wave. If he wishes
a high note, he must have a short sound wave. This
means that he must push the sliding member all the
way in. It is literally, as well as scientifically, true
that the lengthened trombone gives a long wave
length, while the shortened trombone gives a short
wave length. These are, of course, sound waves
with which we have to do here. In radio we do
LONG SOUND WAVE LENGTH SHORT SOUND WAVE LENGTH
exactly the same thing in tuning. When we wish a
long wave length, we must add more wire or its
equivalent to the serial. If we want a short wave
length we must either have a short serial or subtract
some wire from the serial. To lengthen an aerial
in order to obtain a greater wave length, we have
seen before that we make use of a tuning coil and by
means of the slider which we slide up and down,
we increase the wave length just as the trombone
player does with his instrument. To shorten the
wave length in tuning, it would not be possible to
shorten the serial, as this would be a cumbersome
method ; of course it can be done, but not in actual
practice. We, therefore, have recourse to a con-
denser. The reader should remember that in order
RADIO FOR ALL
to decrease the wave length of an serial, all that is
necessary is to put a condenser in series with the
serial which actually decreases the wave length; it
does not increase it as some people seem to think.
To make this clear, although it is not absolutely and
literally true, just imagine that the condenser in the
aerial circuit, as shown in Fig. 59, acts as a sort of
To end ' .
of coil /
buffer which absorbs a portion of the wave length.
The less condenser we add to the serial, that is, the
less capacity we interpose in the serial circuit, the
lower the wave length will be. The condenser,
therefore, gives us the best practical means to de-
crease the wave length ; this point is quite important
to remember. Suppose you have a long aerial, say
200 feet, in connection with a small tuning coil, or
suppose you have a short serial and live on the tenth
floor of an apartment house. The only available
ground would be the water pipe. This water pipe,
however, would be so long that it would add extra
meters to your wave length, and something must
be done to decrease it, if you wish to receive signals
sent out from a broadcasting station operating on
a short wave length of 360 meters. The only way
you could then tune in would be in the former case
of the long serial, to put a variable condenser
in the serial circuit, or in the other case where you
have a long ground to interpose the condenser
in the ground lead as shown in Fig. 60. As a
rule, in these two instances, at least what is techni-
cally called a twenty-three plate variable conden-
ser should be used. Of course, the tuning coil must
be used as well, but it should be adjusted so that it
is at its lower point. In other words, it should not
add more turns of wire to the serial, which would
again increase the wave length. In most cases, a
few turns will do, depending upon how long your
jerial or lead-in is.
TRIALS, LOOP TRIALS, GROUNDS
WE have had occasion to speak of serials and
grounds before, and we will now go into this inter-
esting study more thoroughly. An serial is used to
intercept radio waves ; that is its sole function in the
receiving set. It does not amplify or make the sig-
nals come in clearer by itself. During the past
twenty-five years hundreds of different serials have
been invented, and there is hardly anything in this
field that has not been tried out. An serial, pro-
perly speaking, is an elevated wire that is well insu-
lated, and is usually placed outside of the building
or house. An serial is one of the most important
parts of a radio installation and should never be
thought of in the light as an unimportant adjunct.
As we said before, the serial has the function to
intercept radio waves. These waves come from
afar, and are often very weak and far apart, and in
order to intercept the waves at all, it is of great
importance that the aerial be of good construction.
If you desired to catch butterflies, you would not
use a net with large holes, because you would know
in advance that with such a net you could not
catch many butterflies. Likewise, if you wish to
catch all the available waves that pass your house or
abode, you must have an serial that does not allow
the trifling energy that you have to leak out. Using
TRIALS, LOOP AERIALS, GROUNDS 109
another and a very good simile, you would not think
of pouring a very precious liquid into a sieve if you
wanted to preserve all that precious liquid. You
would use a good container without any holes in it.
Just so with the serial. Always remember that a
chain is no stronger than its weakest link. Con-
versely a radio outfit is no better than its serial.
An serial can be made of most any metallic wire,
but the best material is either copper or copper-clad
wire, which is copper wire with a thin iron core. A
still better wire to use is a stranded wire, which is
composed of several copper or phosphor bronze
wires twisted together. As a rule, we may say that
the larger the wire, the better it is for radio purposes.
Very thick wires, as a rule, cost much and are very
110 RADIO FOR ALL
heavy, and therefore are not very practicable. A No.
14 B & S gauge wire is a standard as used today and
gives excellent results. For radio broadcasting re-
ception it has been found that a single wire 100 feet
long gives excellent results. Illustrations 61 and 62
show such a type of aerial. The single aerial is prefer-
ably used, because its construction is much simpler
than that of a four-wire aerial which we will describe
IOO FEET LONG
later on. If it is desired to receive from a certain sta-
tion, the wire should point in the direction of that
station ; in other words, if, let us say you live in New
York, and you wish to hear WJZ at Newark, N. J.
(which is west from New York) run your aerial wire
from west to east. The lead-in from the aerial (the
wire connecting the aerial to the outfit) should be
connected to that end of the aerial nearest to Newark.
The free or open end of the aerial, therefore, points
away from Newark ; this is correct, as shown clearly
in Fig. 63. This is a perspective view showing on
which side the lead-in, that is the connection that
TRIALS, LOOP AERIALS, GROUNDS 111
goes from the aerial to the instrument, should
Unless you wish to go to a great deal of incon-
venience, make your lead-in of the same wire as the
main aerial. This may be done very simply with a
single wire serial, for the reason that no soldered
connections are necessary. This is also shown
in Fig. 61 and Fig. 62. The next things to
consider are the insulators, which are quite impor-
tant. The insulator serves to insulate the serial,
and unless we use good ones, a great deal of
energy will leak and thus weaken the recep-
tion. This is particularly the case in rainy weather
where the water, or sometimes sleet, will make a
112 RADIO FOR ALL
semi-conductor and unless the insulator is con-
structed correctly, much leakage will be the result.
We show in Fig. 64* various types of insulators that
may be used. One of the simplest is the ordinary
porcelain cleat, but when this type is chosen, an
unglazed cleat should be avoided. Insist upon get-
Vorcelain cleats in tandem-^
Ti^s^s // /' ^r^
Porcelain strain^ Corrugated ^
insulator ball insulators
ting a glazed cleat which is a better insulator. When
using cleats, put them in tandem, two or three strung
in a row, as shown in Fig. 64. The more insulators
we add, the better the insulation. It is however,
hardly necessary to use more than three in a row.
We next have the small spool insulators, which are
very good and may also be strung in pairs, or sets
of three. Various other types are shown in Fig. 64
and regular radio insulators provided with ribs or
under cuts are preferred these days, because they
AERIALS, LOOP AERIALS, GROUNDS 113
make a longer pathway for the electric current, and
are, therefore, better insulators all the way through.
It may be said here that the longer the aerial insu-
lator, the better the aerial. The mode of fastening
some of these insulators is shown in Fig. 64. The
aerial is usually attached to the insulator, while the
wire is twisted around itself after going through the
hole in the insulator. Such radio insulators as a
rule are quite strong, and when the serial is put up,
it can be well stretched without fear that the
insulator will give way. As a matter of fact, the
wire will give way long before the insulator, if the
latter is perfect.
When putting up an serial, it should be remem-
bered always that the aerial proper must be at least
a foot away from all buildings, barns, trees and the
like. In other words, it should be away from all
objects, whatever their names may be. In order to
do so, it is often necessary to attach a wire to a cor-
nice of the building, let us say, and .extend the wire a
few feet, to which we connect the insulators. The
aerial proper is then connected to the other end of the
insulator, which will give us a certain distance be-
tween the cornice and the actual beginning of
The height of the aerial is often important. It
should always be placed at least 20 to 30 feet above
the ground. Generally speaking, the higher the
aerial, the better the reception. High poles are not
always necessary, although very often a good in-
RADIO FOR ALL
vestment. Such poles, however, as a rule are expen-
sive and most people do not wish to go to such an
expense. If poles become necessary, they should
be put up by someone who knows something about
the erection of poles, because if not put up correctly,
such a pole becomes a dangerous object when it
collapses from its own weight or in a storm. Good
engineering in pole construction is a prime necessity.
As a rule, an asrial in the country may be
stretched from the attic window to a flagpole, or if
such is not at hand, a barn, garage, or even a tree
could be made use of . If a tree is used, some means
must be had to compensate for the swaying of the
tree. Such a method is used in Fig. 65. Here we
have a pulley attached to a tree by means of a rope ;
the end of the serial is then run over this pulley and
a fairly heavy weight secured to the open end, such
AERIALS, LOOP AERIALS, GROUNDS 115
as an old pail filled with stones. As the tree sways
back and forth, more or less serial rope is paid out or
taken in, and a good compensation is thus had. The
weight may be 50 to 100 pounds, and an arrange-
ment of this kind works very well. It goes without
saying that the pulley must be insulated by insula-
tors, all of which is shown in Fig. 65.
When an serial is erected in the city, let us say
on an apartment house, we usually do not have
much trouble in putting up a good wire, providing
the landlord does not object, and few landlords do
these days, as they' are becoming more and more en-
lightened in radio matters. The only thing-that we
may add is that an apartment house serial should
be at least 10 feet above the roof, particularly if
the apartment has steel in its construction. If we
can put up an aerial higher than 10 feet, so much the
better. The aerial should always be stretched taut,
as a sloppy and saggy serial is not only unsightly,
but gives rise to poor reception. See Fig. 62. The
reason is that a saggy serial will swing in the wind,
and it has been found that such an serial will not
bring in sharp signals, due to this very swinging.
It often gives rise to what is called "fading signals,"
in other words, one minute the signals may be clear
and the next minute they will be faint.
For long distance work, and where we have a
very good outfit that has good tuning, we often use a
larger serial, i.e., an serial that gives us more capac-
ity; to be more explicit, an serial that covers more
RADIO FOR ALL
space than a single serial. In Fig. 65 and Fig. 66,
and 66A, we have shown a two and four-wire serial
PULLEY TO RAISE
AND LOWER AERIAL
Fra. 66 A.
of the inverted L type. These serials are simply
duplications of the single wire serial, except that
more wires are used. With such serials it is always
AERIALS, LOOP TRIALS, GROUNDS 117
necessary to solder the connections or otherwise use
an antenna connector as shown in Fig. 67. The types
of serial as shown in Fig. 65, 66 and 66A are com-
monly called the inverted L, due to their similarity
to the letter L, turned upside down. Such an aerial
is directive, the same as a single wire aerial, as shown
in Fig. 63. As in the latter, the inverted L type
must have its lead-in taken from the nearest point to
the broadcasting station. The free end, therefore,
points away from the station that we wish to hear.
Fig. 68, shows a four-wire aerial. This aerial has
no directive properties, and receives signals from
many points of the compass almost equally well.
The only difference here is that the lead-in is taken
from the center of the aerial instead of from the end.
An aerial of this kind may be shorter than a single
RADIO FOR ALL
wire aerial, and the wire in this instance may be 40
or 60 feet long, and excellent results may be had
with such a type. Where we have a multiple wire
serial, a new element comes into its construction, viz.,
the Spreader. This is simply a stick of wood, well
painted to keep it from decaying, upon which the
insulators are strung, as shown in the illustrations.
The wires themselves, should be spaced about two
feet apart. The spreader must of course, be sub-
stantial, so that it will not break under the tension.
A bamboo stick about 1 inch or 1 ]/2 inches in diam-
eter has been found to be ideal for this work. It
is often necessary to take down the serial when
we have poles, and for this purpose we use pulleys,
as shown in Fig. 68, by means of which the serial
may be raised and lowered when necessary. In
TRIALS, LOOP AERIALS, GROUNDS 119
Fig. 68 we also see two pieces of cord or rope at-
tached to the spreaders which are put there for the
purpose of keeping the serial from swinging side-
ways or turning over as would be the result if there
was nothing to prevent it. Therefore, stays
The lead-in is that part of the asrial that goes
into the building or house to establish connection
with the instruments. In a single- wire serial, the
lead-in is simply the serial wire itself leading into
the house and thence to the instruments. With a
two, three and four-wire serial, the lead-in is con-
nected to the antenna connector described in Fig.
67, and from that point runs on to the instruments.
The lead-in wire should be of the same size as the
aerial. In other words, about No. 14 B & S wire.
It should be insulated at the point where it nears
the building, or if this is not possible in the case of
a single-wire serial, the lead-in is then strung on
insulators, the wire being always at least one foot
away from buildings, walls, etc., until it reaches the
point where actual entrance is made into the build-
ing; at this point several things arise. We may
bring the wire in through the open window, which,
however, is always considered bad practice. It
should only be done for temporary work. One of
the simplest ways is to drill a hole in the center of the
window pane at the very upper part of the window,
and let the wire come in through this hole, which,
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however, is not such a good practice either, for
the simple reason that it becomes impossible to
lower the window, as the wire will obstruct it. The
best way is to drill a hole through the sash of the
window at any convenient point where the window
weights will not be interfered with. This hole can
be about three quarters of an inch. Into this hole,
set * I
^ _ Drip for rain water
ja^ Cross section of window sosh
fit an ordinary porcelain tube which may be secured
from any electrical supply house. The lead-in is
then fed through this tube, and thence on insulators
to the instruments ; Fig. 68- A makes this clear. If
we do not wish to drill such a large hole through the
window sash, a small one may be made instead, in
which case, we must use a piece of rubber insulated
cable, such as is used on automobiles and this is fed
through the small hole. The actual lead-in wire is
then soldered on the outside of the window to make
/ERIALS, LOOP TRIALS, GROUNDS 121
connection with the automobile cable so that no
part of the bare wire touches the wood work or stone
work near the window. The insulated rubber cable
is then carried along insulators to the instruments.
It should be remembered that the serial wire must
always be well insulated, and that it cannot be insu-
lated too well. Always bear in mind that we have
but little energy coming in over the ferial, and the
better we insulate the lead-in the better the results
We again wish to point out here that for radio
telephone reception a single-wire aerial of 100 to 150
feet long is always the best, whether used with a
crystal outfit or with a vacuum tube set. The rea-
son for this is not because the single aerial wire is
inherently better, but because with it there is less
interference on account of its directional properties.
It has come to the author's attention that many peo-
ple, when buying a small crystal set, are disappoint-
ed because they are not able to receive signals, but
do receive radio telephone concerts. Many people
desire to receive signals as well, as for instance the
Arlington time signals, market reports that are sent
out in code, etc. To all these people we say that
if they desire to receive signals as well as radio tele-
phony, they should use a two or four-wire serial.
They should, however, not complain if, when receiv-
ing radiophone entertainment, signals come in at
the same time ; this often happens with a two or four-
wire aerial, and unless the instrument used is a very
RADIO FOR ALL
selective one, it is not always possible to tune out
the unwanted station that sends in code. This is
especially true of crystal sets where it is impossible
to tune quite so sharply as with vacuum tube sets.
There is still another type of serial that was used
at one time extensively, and although it is not used
so much today, it has a great deal of merit. We
refer to the Umbrella .zErial as shown in Fig. 69.
This serial as its name implies, is in the form of an
umbrella, and may be made of any size, but should
never be less than 25 feet high, 50 or 75 and even
100 feet, being better. In the umbrella serial we have
TRIALS, LOOP TRIALS, GROUNDS 123
a single mast, from the top of which emerge single
wires in all directions. The connections are made
as shown in the illustration. This aerial has a great
advantage in being able to receive from all direc-
tions equally well. As we have noted before, the
single-wire ferial receives with maximum intensity
from one direction. The umbrella aerial, however,
receives from all points of the compass with equal
facility. It is also possible by a switching arrange-
ment to connect any one of the serial wires of the
umbrella antenna in order to get rid of interference.
This means, of course, an elaborate switching ar-
RADIO FOR ALL
rangement, which is not very often within the reach
of the layman, by whom such an aerial is rarely, if
TRIALS, LOOP AERIALS, GROUNDS 125
ever used. To the man, however, who desires to go
in for experimental work such an serial has its uses,
and will repay the labor spent in constructing it.
We now come to an serial which is entirely differ-
ent from those of which we have spoken before. We
refer to the loop aerial, which is shown in Fig. 70.
It should be understood that a loop serial is hardly,
if ever, used in connection with a crystal set. It
is used almost exclusively with a vacuum tube set,
as will be explained further on. The loop serial
serves several purposes. In the first place it does
away with the ground connection. Secondly, the
loop serial may be made in any size from one foot
square up to 20 feet square. The loop aerial is
highly directive ; by that we mean that it will only
receive with maximum intensity if the loop is turned
in the direction of the coming signals. This is
shown clearly in Fig. 71. Here we see how an or-
dinary loop serial is placed in a building, and we also
see how the waves are propagated from a distant
sending station. It will be found that the signals
are strongest when the loop points exactly in the
direction from which the waves are coming. The
loop aerial, therefore, serves the additional purpose
of telling from which direction the waves are com-
ing, and this principle is made use of in the
All the ships that come from points far away
do not compute their own bearings any longer, but,
by means of radio, call the nearest compass station.
126 RADIO FOR ALL
There are usually several of these stations placed
at various points along the coast, and by means of
their radio direction finder, the personnel at the sta-
tion turn the loop until they hear the ship with maxi-
mum intensity; the loop is then pointing directly
to the ship. The station further down the coast
does the same thing, while the two stations com-
municate with each other by telephone or telegraph.
By means of triangulation the operators then cal-
culate within a few minutes just exactly where the
ship is located. Within one or two minutes at the
latest one of the land stations radios to the ship, tel-
ling at what latitude and longitude it is ? The posi-
tion can be ascertained within a few hundred feet,
a thing impossible for any captain to do with his
compass, or by other means. Fig. 73, shows the
radio compass graphically.
AERIALS, LOOP TRIALS, GROUNDS
As to the loop serial itself, as we have already
mentioned, its size depends upon the builder. It is
usually made up of a frame as shown in Fig. 70,
and this frame may be from 2 to 4 inches square.
Upon the frame are usually wound about six to ten
turns of insulated wire, the two ends coming out
somewhere near the center and connecting with the
instruments. Fig. 72 shows the simplest connection
of a loop aerial, with the simplest regenerative va-
cuum tube hook-up.
While in this diagram the loop aerial is shown, it
should be distinctly understood that a loop asrial is
not of much use unless we have at least two or three
stages of amplification. The reason is that the loop
asrial, being as a rule very small, its capacity is na-
turally small, and but few waves strike it. There-
fore, it becomes necessary to amplify the exceed-
ingly weak currents. The connection shown in
RADIO FOR ALL
Fig. 72 is only good if we are located but a few miles
from the broadcasting station. For longer dis-
tances, we must have several stages of amplification
as already mentioned. Tuning with the loop aerial
is rather difficult because, as mentioned before, the
serial must point exactly in the direction from which
the signals come. Moving the loop even a few
Rubber insulated wire
inside iron pipe .. ^-
inches to the side will cut off all the signals. The
best position, therefore, must always be found
We come now to still another aerial which is the
least used, but which has its advantages; we refer
to the underground serial. Fig. 74 shows the prin-
ciple, which consists of a well insulated wire, usually
a rubber covered automobile cable. A trench about
two to three feet deep is dug in a straight line run-
ning in the same direction from which the signals
are expected to be received. The wire is then care-
fully insulated at the open end and run through an
TRIALS, LOOP AERIALS, GROUNDS 129
iron pipe. Both are then placed at the bottom of
the trench. Such a wire must be at least 200 feet
long to get fair results. After the trench is cov-
ered over again the other end is led into the station,
and connected with the instruments, the same as the
usual serial. A ground must be used with this serial,
which will only receive signals from the direction in
which it points or points away from. It can of
course not be used much in the city, but is desirable
in the country if a pole or overhead wires are not
wanted. The underground serial has the very great
advantage of being almost entirely free from static
and atmospheric disturbances. Thus, for instance,
Dr. James Harris Rogers, the inventor of the under-
ground serial during the war, received excellent sig-
nals from Nauen, Germany, as well as other
European centers while a thunderstorm was raging
overhead. Of course, it goes without saying that
an overhead serial cannot be used during a thunder
storm because it becomes extremely dangerous to
the user. With the underground serial such risk
is entirely eliminated.
Not only that, but in the summertime the over-
head serials give quite a good deal of trouble, due
to static and atmospheric electricity, even though
there is a blue sky overhead. As we have already
mentioned in another chapter, in the summertime
the atmosphere is continually charged with electric-
ity, and this electricity discharges through the serial
wire and gives rise to crackling sounds in the re-
130 RADIO FOR ALL
ceivers which often become unbearable. So far,
nothing has been invented to do away with these
parasitic currents, technically called X or static.
How TO FIGURE WAVE LENGTHS OF
Each aerial used for transmitting and receiving
has a wave length of its own. It depends upon
several factors beside its dimensions and it is prac-
tically impossible to calculate it accurately unless
a measuring instrument is used. The wave length
depends upon the length of the wire composing the
aerial taken from the ground to the free end of the
wire. If it is composed of several wires, the num-
ber and spacing of these wires also influence the
wave length as well as the distance of the straight
portion from the ground, and the shape of the
The wave length of a single- wire aerial is, rough-
ly, four times the length of the wire from the ground
to the free end measured in meters. For instance, if
a single-wire serial 100 feet long, is erected 50 feet
above the ground with the lead-in that is vertical, the
total length of the wire will be 150 feet or 45 meters.
The wave length will consequently be 45X4=
The wave length of an aerial depends upon the
nature of the ground above which it is erected and
the objects interposed between the flat portion call-
ed the flat-top and the ground. If an aerial is erected
above the house, its natural wave length will be
different from what it would be if erected in a field
TRIALS, LOOP TRIALS, GROUNDS 131
without any obstruction in the neighborhood. For
this reason, no formula can be given that will be
accurate enough to tell this, and the only practical
means of measuring the natural wave length of an
serial is by means of a wave meter.
Natural Wave Lengths
of 4 wire T aerials
60 80 100 120 140 160 180 200 220 240
Horizontal length of aerial in feet
FIG. 74 A.
The accompanying charts shown in Figs. 74A
and 74B have been compiled by taking the average
wave length of several serials of the same size erect-
ed at different places and give sufficient accurate
measurements for the ordinary types of antenna?
used by amateurs. Fig. 74A shows the natural
wave length of an serial of the "T" type, that is,
those of which the lead-in is taken from the exact
center. Above each curve is marked the height
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from the ground to which it corresponds. Fig. 74B
gives the wave length for serials of the inverted
"L" type, that is, those having the lead-in taken
from one end of the wires. The free ends of the
serial wires are in both cases free. That is, with-
out connections across on the wires.
Natural Wave Lengths
of 4 wire inverted L aerials.
30 40 50 60 70 80 90 100 110
Horizontal length of aerial in feet.
Fia. 74 B.
To find out the wave length of an inverted "L"
serial 100 feet long and 40 feet above the ground,
we refer to Fig. 74B, and by means of a rule we
measure on the scale indicating the wave length,
how many meters correspond horizontally to the
point where 100 feet in length crosses 40 feet
in height. This gives us approximately 175 meters
TRIALS, LOOP TRIALS, GROUNDS 133
In radio, in connection with the usual aerial, it
becomes necessary to use a ground, which, as its
name implies, is a connection made with the earth.
The earth being a good conductor, it is often used
as a sort of return circuit, and it has been found,
that, with the ordinary circuits, signals come in very
much better if such a ground is used. It is possible
to use an aerial without a ground for short distances,
in which case it becomes a sort of loop. For ordin-
ary purposes, however, it would be impossible to
use a radio outfit without a ground connection.
Fig. 75 shows the simplest and perhaps the best.
It is simply a wire fastened to the cold water pipe,
which is found in almost every house and apartment.
In order to make a good connection, we use a ground
clamp, as shown in Fig. 76. This ground clamp
is simply a piece of metal band wrapped around
RADIO FOR ALL
the water pipe, which should first be scraped with a
file or old knife, the idea being to obtain a perfectly
clean metallic connection. By means of some
clamping arrangement, which differs for every
ground clamp, a strong mechanical connection is
made. The ground wire is then fastened to the
screw or binding post attached to the ground clamp.
The ground wire need not be insulated. An ordin-
ary bare No. 14 B & S wire will do nicely; in other
words, the same wire which we use on an serial may
be used. It is not necessary to run the ground wire
on insulators, as is done with the aerial lead-in, but
it may be attached to the wall by means of nails
which serve the purpose equally well. Of course,
the ground wire should not be longer that is abso-
lutely necessary. If it is not possible to find a cold
AERIALS, LOOP TRIALS, GROUNDS 135
water pipe, a radiator pipe may be used, although
the results may not be as good as from the cold water
pipe. It is against the law to connect a ground to
a gas pipe, and it should therefore never be done.
In the first place you encourage fire danger, and
secondly the gas ground connection is never as effi-
cient, for the reason that the pipe does not run di-
rectly into the soil. Usually such gas pipes go first
to a gas meter which, due to leather washers and
lead paint, often insulate the pipe from the ground,
and therefore the results with a gas ground are often
very poor. For these reasons it is never advisable to
use such a ground except in emergency, but never
for permanent use.
When we are out in the country, for instance,
when camping, it is not always possible to have a
136 RADIO FOR ALL
water pipe, and in that case we have to establish
contact with Mother Earth direct. This is usually
accomplished by driving a metal rod into moist
earth, as is shown in Fig. 77. A "ground" of this
sort is nothing but an iron, brass or other metallic
rod sharpened at the end and driven anywhere from
18 to 36 inches into the soil. The wire to make con-
nection may be soldered, or may have a binding
post or a ground clamp just as on a water pipe.
A ground of this kind will not work unless it is
actually driven into the moist soil. It is thus neces-
sary to do two things : first, we may pour a large
quantity of water near the grounding rod to make
sure that the earth becomes moist for quite a dis-
tance surrounding the rod. Even by applying this
artifice it is not always possible to obtain results
because the underlying strata may be devoid of
moisture, and it will then not be possible to receive
signals; this is especially the case on many hill-tops.
When such conditions arise, it becomes necessary to
move the ground until we actually reach a wet spot
such as, for instance, in the immediate vicinity of a
natural well, the shore of a creek or a small body of
water such as a pond or a lake; these all make
In farm houses where no water pipe exists it
is usually best to drive a gas or water pipe from
1 to 1 }/2 inches in diameter into moist soil. Connec-
tion is established by means of a ground clamp, as
AERIALS, LOOP AERIALS, GROUNDS 137
The question is often asked how ships or motor
boats can have a ground. The answer to this is that
the ground connection is always attached to the
outside metallic plating of the ship or motor hoat.
The connection should always be soldered. Such
a ground is really a very excellent one, and will
GROUNDS IN APARTMENT HOUSES
It should be understood that there are grounds
and grounds. The reason is as follows. A long
ground, by reason of its length, has a certain effect
upon the receiving outfit on account of its own wave-
length. If we have but a short ground, say ten or
fifteen feet long, its wave-length is minimum. But
consider Fig. 78. Here we have an aerial, say 50
feet long, on top of a ten-story apartment house.
The owner of this outfit, let us say, lives on the tenth
floor. If we trace the ground down to the soil,
we will find a water pipe anywhere from 100
feet to 120 feet long. What is the result? Such
a long ground will add about 740 meters wave-
length to the outfit, and will in fact, overshadow the
serial to such an extent that the ground becomes
longer than the serial. This is very poor practice,
but it cannot, of course, always be helped. It has
been found that where such an occasion prevails,
the usual outfits sold on the market do not work very
well because they are not built to operate on such
a wave length. In order to use an outfit with such
a long asrial, it becomes necessary to install a var-
RADIO FOR ALL
iable condenser in series with the ground wire in or-
der to overcome the handicap. See Fig. 60. By
adjusting the variable condenser, a point will be
found where the signals come in best. The conden-
ser, in other words, cuts down the wave-length to
a point where it counter-balances the excessive
wave-length of the ground. Such a condenser
should always be used when there is a long ground,
as for instance, in apartment houses, high office
2ERIALS, LOOP JERIALS, GROUNDS 139
The properly installed serial, when used with a
lightning arrester, is the best protection a building
or house could have against lightning. Always re-
member that the serial is nothing but a lightning
conductor itself, and will actually protect the house,
and will never endanger it if properly installed.
An serial will draw the atmospheric electricity si-
lently to the ground, and there are very few authen-
tic cases on record where lightning has actually
struck an serial. If it did strike it, it usually did very
little damage because the lightning spent itself
through the lightning arrester or lightning switch
down to the ground. In former years, it was nec-
essary to use a lightning switch by which, in a thun-
der storm, it became necessary to connect the serial
directly to the ground. Recent regulations, how-
ever, make it unnecessary for owners of a radio re-
ceiving outfit to have a lightning switch, although it
is a good precaution and we give below the present
Federal regulations for installation of lightning
The lightning arrester itself is nothing but a
small spark gap either in a vacuum or in the atmos-
phere, which gap breaks down when a current of
a few hundred volts strikes the serial. Instead of
going through the instruments which have a high
resistance, the current travels direct to the ground,
which has a low resistance. Secondly, the instru-
RADIO FOR ALL
ments are not damaged. In Fig. 79 are shown the
various types of lightning arrester. Fig. 61 shows
the connections. The lightning regulations follow
In setting up radio equipment all wiring pertaining thereto must
conform to the general requirements of this code for the class of work
installed and the following additional specifications:
FOR RECEIVING STATIONS ONLY
(a) Antennae outside of buildings shall not cross over or under
electric light or power wires of any circuit of more than six hundred
(600) volts or railway trolley or feeder wires, nor shall it be so lo-
cated that a failure of either antenna or of the above mentioned
electric light or power wires can result in a contact between the
antenna and such electric light or power wires.
Antennae shall be constructed and installed in a strong and durable
manner and shall be so located as to prevent accidental contact with
light and power by sagging or swinging.
Splices and joints in the antenna span, unless made with approved
clamps and splicing devices, shall be soldered.
Antennas installed inside of buildings are not covered by the
TRIALS, LOOP TRIALS, GROUNDS 141
(b) Lead-in wires shall be of copper, approved copper-clad steel
or other approved metal, which will not corrode excessively and in no
case shall they be smaller than No. 14 B. & S. gage except that ap-
proved copper-clad steel not less than No. 17 B. & S. gage may
Lead-in wires on the outside of buildings shall not come nearer
than four (4) inches to electric light and power wires unless sep-
arated therefrom by a continuous and firmly fixed non-conductor that
will maintain permanent separation. The non-conductor shall be in
addition to any insulation on the wire.
Lead-in wires shall enter building through a non-combustible, non-
absorptive insulating bushing.
(c) Each lead-in wire shall be provided with an approved pro-
tective device properly connected and located (inside and outside the
building) as near as practicable to the point where the wire enters the
building. The protector shall not be placed in the immediate vicinity
of easily ignitable stuff, or where exposed to inflammable gases or
dust or flying combustible materials.
The protective device shall be an approved lightning arrester which
will operate at a potential of five hundred (500) volts or less.
The use of an antenna grounding switch is desirable, but does not
obviate the necessity for the approved protective device required in
this section. The antenna grounding switch, if installed, shall, in its
closed position, form a shunt around the protective device.
PROTECTIVE GROUND WIRE
(d) The ground wire may be bare or insulated and shall be of
copper or approved copper-clad steel. If of copper the ground wire
shall be not smaller than No. 14 B. & S. gage and if of approved
copper clad steel it shall be not smaller than No. 17 B. & S. gage.
The ground wire shall be run in as straight a line as possible to a good
permanent ground. Preference shall be given to water piping. Gas
piping shall not be used for grounding protective device. Other per-
missible grounds are grounded steel frames of buildings or other
grounded metallic work in the building and artificial grounds such as
driven pipes, plates, cones, etc.
The ground wire shall be protected against mechanical injury. An
approved ground clamp shall be used wherever the ground wire is
connected to pipes or piping.
142 RADIO FOR ALL
WIRES INSIDE BUILDINGS
(e) Wires inside buildings shall be securely fastened in a work-
manlike manner and shall not come nearer than two (2) inches to any
electric light or power wire unless separated therefrom by some con-
tinuous and firmly fixed non-conductor making a permanent separa-
tion. This non-conductor shall be in addition to any regular insulation
on the wire. Porcelain tubing or approved flexible tubing may be
used fcr encasing wires to comply with this rule.
RECEIVING EQUIPMENT GROUND WIRE
(f) The ground conductor may be bare or insulated and shall be
of copper, approved copper-clad steel or other approved metal which
will not corrode excessively under existing conditions ; and in no case
shall the ground wire be less than No. 14 B. & S. gage except that
approved copper-clad steel not less than No. 17 B. & S. gage may
The ground wire may be run inside or outside of building. When
receiving equipment ground wire is run in full compliance with rules
for protective ground wire, in Section d, it may be used as the ground
conductor for the protective device.
FOR TRANSMITTING STATIONS
(g) Antennae outside of buildings shall not cross over or under
electric light or power wires of any circuit of more than six hundred
(600) volts or railway trolley, or feeder wires nor shall it be so located
that a failure of either the antenna or of the above mentioned electric
light or power wires can result in a contact between the antenna and
such electric light or power wires.
Antennae shall be constructed and installed in a strong and durable
manner and shall be so located as to prevent accidental contact with
light and power wires by sagging or swinging.
Splices and joints in the antenna span shall, unless made with
approved clamps or splicing devices, be soldered.
(h) Lead-in wires shall be of copper, approved copper-clad steel
or other metal, which will not corrode excessively and in no case shall
they be smaller than No. 14 B. & S. gage.
Antenna and counterpoise conductors and wires leading therefrom
to ground switch, where attached to buildings, must be firmly mounted
five (5) inches clear of the surface of the building on non-absorptive
TRIALS, LOOP AERIALS, GROUNDS 143
insulating supports such as treated wood pins or brackets equipped
with insulators having not less than five (5) inch creepage and air
gap distance to inflammable or conducting material. Where desired,
approved suspension type insulators may be used.
(i) In 'passing the antenna or counterpoise lead-in into the build-
ing, a tube or bushing of non-absorptive insulating material shall be
used and shall be installed so as to have a creepage and air-gap dis-
tance of at least five (5) inches to any extraneous body. If porcelain
or other fragile material is used, it shall be installed so as to be pro-
tected from mechanical injury. A drilled window pane may be used
in place of bushing, provided five (5) inch creepage and air-gap
distance is maintained.
PROTECTIVE GROUNDING SWITCH
(j) A double-throw knife switch having a break distance of
four (4) inches and a blade not less than one-eighth (%) inch by one-
half (%) inch shall be used to join the antenna and counterpoise
lead-ins to the ground conductor. The switch may be located inside or
outside the building. The base of the switch shall be of non-
absorptive insulating material. Slate base switches are not recom-
mended. This switch must be so mounted that its current-carrying
parts will be at least five (5) inches clear of the building wall or
other conductors and located preferably in the most direct line be-
tween the lead-in conductors and the point where ground connection
is made. The conductor from grounding switch to ground connection
must be seciirely supported.
PROTECTIVE GROUND WIRE
(k) Antenna and counterpoise conductors must be effectively and
permanently grounded at all times when station is not in actual oper-
ation (unattended) by a conductor at least as large as the lead-in,
and in no case shall it be smaller than No. 14 B. & S. gage copper or
approved copper-clad steel. This ground wire need not be insulated
or mounted on insulating supports. The ground wire shall be run in
as straight a line as possible to a good permanent ground. Preference
shall be given to water piping. Gas piping shall not be used for the
ground connection. Other permissible grounds are the grounded steel
frames of buildings and other grounded metal work in buildings and
artificial grounding devices such as driven pipes, plates, cones, etc.
The ground wire shall be protected against mechanical injury. An
approved ground clamp shall be used wherever the ground wire is
connected to pipes or piping.
144 RADIO FOR ALL
OPERATING GROUND WIRE
(1) The radio operating ground conductor shall be of copper strip
not less than three-eighths (%) inch wide by one-sixty-fourth (1/64,)
inch thick, or of copper or approved copper-clad steel having a peri-
phery, or girth (around the outside) of at least three-quarters (%)
inch (for example a No. 2 B. & S. gage wire), and shall be firmly
secured in place throughout its length. The radio operating ground
conductor shall be protected and supported similar to the lead-
(m) The operating ground conductor shall be connected to a good
permanent ground. Preference shall be given to water piping. Gas
piping shall not be used for ground connections. Other permissible
grounds are grounded steel frames of buildings or other grounded
metal work in the building and artificial grounding devices such as
driven pipes, plates, cones, etc.
POWER FROM STREET MAINS
(n) When the current supply is obtained directly from street
mains, the circuit shall be installed in approved metal conduit, armored
cable or metal raceways.
If lead covered wire is used, it shall be protected throughout its
length in approved metal conduit or metal raceways.
PROTECTION FROM SURGES, ETC.
(o) In order to protect the supply system from high-potential
surges and kick-backs, there must be installed in the supply line as
near as possible to each radio-transformer, rotary spark gap, motor-
generator sets and other auxiliary apparatus one of the following:
1. Two condensers (each of not less than one-half (%) microfarad
capacity and capable of withstanding six hundred (600 volt test) in
series across the line and mid-point between condensers grounded;
across (in parallel with) each of these condensers shall be connected
a shunting fixed spark gap capable of not more than one-thirty-second
(1/32) inch separation.
2. Two vacuum tube type protectors in series across the line with
the mid-point grounded.
3. Non-inductively wound resistors connected across the line with
4. Electrolytic lightning arresters such as the aluminum cell type.
In no case shall the ground wire of surge and kick-back pro-
AERIALS, LOOP TRIALS, GROUNDS 145
tective devices be run in parallel with the operating ground wire when
within a distance of thirty (30) feet
The ground wire of the surge and kick-back protective devices
shall not be connected to the operating ground or ground wire.
(p) Transformers, voltage reducers, keys, and other devices em-
ployed shall be of types suitable for radio operation.
These rules do not apply to radio equipment installed on ship-
board, but have been prepared with reference to land stations.
(a) Antenna Indoor receiving antennae are not included within
the requirements of this proposed rule, which provides for the pro-
tection of radio equipment against lightning. Indoor receiving
antennae and auxiliary apparatus are, however, included in the general
requirements covering the wiring of signal systems, for it is obviously
desirable to insure, for example, the freedom of all receiving apparatus
from contact with electrical power circuits either inside or outside
It is desirable that electrical construction companies install radio
antennae and apparatus for persons who are not familiar with electric
wiring. This will tend to insure the installation of antennae and
apparatus in a strong and durable manner. It is important that an-
tenna wire be used in such size and tensile strength as to avoid its
coming in contact with any electric power wires whatsoever.
The size and material of which the antenna is made should depend,
to some extent, upon the length of the span which the antenna must
bridge. It is suggested that for the ordinary receiving antenna about
100 feet long No. 14 B. & S. gage soft drawn copper wire can safely
be used. If other materials are used, the size which is chosen should
be such as to insure tensile strength at least equal to that of the
No. 14 soft copper wire suggested above.
The requirements covering splices and joints in the antenna span
are for the purposes of avoiding accidental falling of such wires upon
light and power wires, of less than 600 volts where it is found neces-
sary to cross such lines. The rules, it will be noted, permit crossings
with lines of 600 volts or less, if they do not happen to be trolley
wires or feeders to trolley wires. In such a case, it is desirable to use
wire of a larger size than 14 B. & S. gage in order to minimize the
chance of accidental contact of the antenna with the power wires.
The interchangeable use of copper and of approved copper-clad
conductor is suggested on account of the fact that these two kinds of
146 RADIO FOR ALL
wire are practically equivalent in their conductivity for high-
(b) Lead-in Wires No mention is made of the insulation from the
building of the receiving antenna or lead-in wire except that this
lead-in wire should be run through a bushing. The latter provision
is chiefly to protect the wiring against the possibility of short-
circuiting with electric power lines which may run in the wall and
whose location may be unknown to the persons installing the radio
equipment. This requirement serves also to protect the antenna lead-
in wire against contact with metal lath or other metal parts of
From a signaling standpoint, it is desirable to use insulators for
receiving antennae in order that wet weather may not cause the an-
tenna to become partly short-circuited to the ground.
(c) Protective Device The requirement for a protective device
to be connected between the antenna and ground terminals of the re-
ceiving set is for the purpose of carrying lightning discharges or less
violent discharges caused by induction or by atmospheric electricity
to the ground with a minimum chance of damage to the receiving
apparatus, building, or operator. A fuse is not required as a part
of the protective device, though lightning arresters which are provided
with fuses will not necessarily fail to receive approval. If a fused
lightning arrester is used, it makes it less likely that the antenna
terminals of a receiving set will be put in a high voltage in case the
antenna falls upon an electric light or power wire. The absence of
the fuse, on the other hand, makes it possible for the antenna, if it
accidentally falls across the power wires, to become fused at the point
of contact and thus fall to the ground and eliminate the hazard. The
antenna terminal of the receiving set should be connected to the point
of junction of the fuse with the arrester.
Lightning arresters may be used inside the building, and in such a
case they will receive better protection from moisture and mechanical
injury than lightning arresters placed on the outside of a build-
Protective devices of reliable manufacture are approved by the
Underwriters' Laboratories, and can be depended upon to operate at
the required voltage. The use of a cheaply constructed home-made
arrester is not recommended, since it may easily get out of order and
fail to operate at the low voltage which is desirable. Arresters should
be inclosed in such a way as to protect the breakdown gap from dust
One disadvantage of the vacuum tube type of arrester is that it may
cease to function without giving warning that it is inoperative. A
AERIALS, LOOP AERIALS, GROUNDS 147
list of the approved protective devices and ground clamps is contained
in the "List of Inspected Electrical Appliances," published by the
Underwriters' Laboratories. This list is revised semi-annually and
may be consulted upon application to the principal office of the Under-
writers' Laboratories, Inc., 207 East Ohio St., Chicago, 111., and at
offices and agencies throughout the United States and Canada.
While an arrester connected between the antenna and ground is
regarded by many as sufficient protection, it is somewhat safer to in-
stall a switch in parallel with it as an added protection. Particularly
if the arrester is inside of the building and the ground connection is
made to a radiator, it is desirable to use in addition the outside
If the antenna is properly connected to the ground, such connec-
tion prevents the antenna from becoming a hazard to the building and
its contents and may act to supplement the protection given by
lightning rods. The arrester should have the most direct connection to
the ground which it is feasible to make, otherwise the antenna may be-
come a hazard with respect to lightning.
(d) Protective Ground Wire While it is desirable to run the pro-
tective ground wire in as direct a line to ground as possible, it is
more important to provide a satisfactory contact at the ground itself
than to avoid a few bends in the ground wire.
(f) Receiving Equipment Ground Wire If the ground wire of a
receiving set passes through a wall it should be insulated for the same
reasons as the antenna lead-in wire referred to in paragraph
If the ground wire is exposed at all to mechanical injury it should
be of larger size than the minimum permitted under the rules and
certainly not smaller than No. 10 B. & S. gage. It should, for mechani-
cal protection, be enclosed in wood moulding or other insulating
material. Ground wires should not be run through iron pipe or con-
duit because of the choking effect at radio and lightning frequencies.
(j) Protective Ground Switch On account of the larger size of
the ordinary transmitting antenna, it is more likely to be subject to
damage from lightning; and on account of the high voltages produced
by radio transmitting equipment, it is desirable to provide for the
use of a double-throw switch for connecting the antenna either to the
transmitting apparatus or to the ground. The use of this switch
makes it possible to entirely disconnect the antenna from the trans-
mitting apparatus when not in use.
148 RADIO FOR ALL
The objection to slate-base switches is chiefly from the radio
engineering viewpoint, on account of the absorption of water by
many kinds of slate and the presence of conducting streaks.
Under this rule one has the choice of the standard 100-ampere
600-volt single-pole, double throw switch or a special antenna switch
using 60-ampere copper which has an air-gap distance of at least
(o) Protection from Surges, etc. On account of the difficulty
which has been experienced by the induction of voltages in the supply
lines of a transmitting station, it is advisable to use a protective
device across the terminals of each machine or transformer connected
to this power line. It would also seem desirable to connect a similar
protective device across the power line and near the point of its
entrance to the building and on the house side of the meters.
It is desirable that research on the performance of protective de-
vices and the means of avoiding surges and " kick-backs " in the power
supply lines be promoted.
For further suggestions regarding good and bad practice in the
installation and maintenance of signal wires and equipment, reference
should be made to "National Electrical Safety Code, 3rd Edition,
October 31, 1920, Bureau of Standards Handbook No. 3 " and espe-
cially Section 39. This is obtainable from the Superintendent of
Documents, Government Printing Office, Washington, D. C.
The 1920 edition of the " National Electrical Code," which contains
the regulations of the National Board of Fire Underwriters, includ-
ing Rule 86, which is now the rule in effect covering radio signaling
apparatus, may be referred to at any local inspection department of
the fire underwriters, or may be purchased from the National Board
of Fire Underwriters, 76 William St., New York City.
Mme. Olga Petrova, famous actress, authoress of the play "White Peacock" recently entertained
through WJZ, the Westinghouse Radio Corp. Broadcasting Station at
Newark, by si _' _
next day she received 968 very complimentary letters from the invisible audience.
her largest audience
Newark, by singing several songs and telling stories about her _stage and screen su
RADIO DIAGRAMS AND HOW TO
HERETOFORE in our illustrations we have shown
perspective views of all the instruments and how
they are wired together, etc. As the reader becomes
more familiar with radio matters, he should take
up the study of diagrams because a glance at one
will show the connections. A radio diagram is to
a perspective drawing what stenography is to long
hand. Radio diagrams give us the means to tell
at a glance what the connections of the various in-
struments are, and as a matter of fact it is much
simpler to read a diagram than a perspective draw-
ing. It is much harder to read a perspective draw-
ing than a diagram because in the former, such as
we have shown heretofore, there is nothing but a
maze of wires, one crossing the other, and one really
never knows where one is. The diagram on the
other hand simplifies matters a great deal and it
becomes a comparatively easy matter to trace a cir-
cuit by means of the diagram. Certain symbols
are used to describe apparatus and in our illustra-
tions 80 to 85, we have shown the various symbols
graphically. By studying these symbols and mem-
orizing them, it becomes a simple matter to trace the
various circuits and study the diagrams.
Diagrams and circuits form a great chapter by
themselves, and it is not within the range of this
RADIO FOR ALL
J.I.LI.I 1 I
1 1 ! II II
book to cover all points, because a number of books
could be obtained on vacuum tube diagrams alone,
and for this reason we will not go deeply into the
RADIO DIAGRAMS, HOW TO READ THEM 151
matter. Suffice it to say that the diagrams which
are shown on the following pages all have a reason
for being, and all are the outcome of many thou-
RADIO FOR ALL
sands of experiments. The diagrams shown have
been selected and in order that the reader may fam-
iliarize himself with them, the captions under the
RADIO DIAGRAMS, HOW TO READ THEM 153
diagrams show to which perspective drawing in
the front of the book they refer. The diagram of
FIG. 86. REFER TO Fio. 7.
Fro. 87. REFER TO Fio. 10.
the perspective drawing, therefore, may be com-
pared and the circuits traced. The reader should
take a pad and paper and trace a few diagrams
RADIO FOR ALL
himself in order to become acquainted with the va-
rious circuits. It should be understood, of course,
that not all connections that the reader will think
Fro. 88. REFEB TO FIQ. 18.
Fio. 89. Buna TO FIG. 19.
of will work. There are certain fundamentals in
radio which must be observed, and there are reasons
for them all. For instance, it makes a great differ-
ence in what part of the circuit the crystal detector
RADIO DIAGRAMS, HOW TO READ THEM 155
Fio. 90. REFEB TO Fio. 22.
Fio. 91. REFEB TO Fio.
or telephone is placed. All these points have been
studied in the past and certain definite results have
RADIO FOR ALL
FIG. 93. REFEB TO Fia. S3.'
been achieved. Of course, the reader is encouraged
to experiment in his own way by connecting his in-
struments in various combinations, which are almost
RADIO DIAGRAMS, HOW TO READ THEM 157
Fio. 96. REFEB TO Flo. 87.
endless, but he will find that the diagrams as we
show them here will work best as a general rule.
The study of radio diagrams is not difficult at
RADIO FOB ALL
Fio. 96. REFEB TO FIG. 47.
FIG. 97. REFEB TO Fio. St.
all, once the fundamentals are clearly understood,
but it is necessary to first memorize symbols, other-
wise not much headway will be made.
For the guidance of the reader, we would first
advise memorizing the following: "asrial, ground,
RADIO DIAGRAMS, HOW TO READ THEM 159
detector, phones." These are the simplest and es-
sential ones, and for that reason, we have shown
Fio. 08. RBFBB TO Fio. 66.
these first in our diagrams. Once the various con-
nections have been mastered, it then becomes a sim-
ple matter to go ahead with the others.
Of course, where the reader is becoming suffi-
ciently interested in radio to be a radio experimen-
RADIO FOR ALL
Fro. 100. BKTKB TO Flo. 50.
To instruments *-
Fio. 101. Ricnta TO Fia. 60.
ter, the study of diagrams will not long remain fas-
cinating. He will wish to make the actual connec-
tions on the instruments himself, and we greatly
RADIO DIAGRAMS, HOW TO READ THEM 161
Vorio- coupler Grid leaK
ri nto ( rvond cond.
r Rheostat -
Fio. 102. RJCFEB TO Fia. 72.
Direct current, generator
Fia. 103. RKFEB TO Fio. 106.
encourage this, and assure every reader that he
will derive more information and satisfaction from
actual connections than from anything else in radio.
RADIO FOR ALL
Grid leaK and condenser
Variable t(S Microphone
FIQ. 104. RETEB TO Fia. 108.
Microphone \ Modulator
FIG. 105. RKFEB TO Fro. 100.
RADIO DIAGRAMS, HOW TO READ THEM 163
In connection with these diagrams, as mentioned
before, in order that the reader may better study
them, we have listed only such diagrams, the per-
spective drawings of which have been shown in other
sections of the book.
Thus the diagram shown in Fig. 86 is shown in
perspective in Fig. 7, Fig. 87 refers to Fig. 10, Fig.
88 refers to Fig. 18, Fig. 89 refers to Fig. 19, Fig.
90 refers to Fig. 22, Fig. 91 refers to Fig. 26, Fig.
92 refers to Fig. 31, Fig. 93 refers to Fig. 33, Fig.
94 refers to Fig. 34, Fig. 95 refers to Fig. 37, Fig.
96 refers to Fig. 47, Fig. 97 refers to Fig. 52, Fig.
98 refers to Fig. 56, Fig. 99 refers to Fig. 57, Fig.
100 refers to Fig. 59, Fig. 101 refers to Fig. 60, Fig.
102 refers to Fig. 72, Fig. 103 refers to Fig. 106;
Fig. 104 refers to Fig. 108, Fig. 105 refers to
It is not the purpose of this book to be of such
a technical nature as to list several hundred dia-
grams, as there are other books making a specialty
of this. The purpose of the few diagrams is merely
to acquaint the reader with the first principles.
We have already mentioned radio telephony
in previous chapters, but not insofar as the trans-
mitting is concerned. We have already learned
that radio telephony is not a new art, but has been
known for many years. The first to send radio tele-
Tuning coil T
To direct current generator
\J I OU I IU ..!.:: .-..-.-.: .v.v-.-J T.-Vr'.'
phone messages over long distances was Valdemar
Poulsen. The important instrument which he used
in his experiments was the electric arc. The dia-
gram of connections is shown in Fig. 106. It was
found that with a suitable arrangement the electric
arc became capable of sending out undamped waves
which are also known under the definition of contin-
uous waves. In other words, the electric arc sends
out a wave that is continuous without interruption.
Mme. Johanna Gadski, famous operatic soprano, singing Wagner's "Elizabeth's Aria from Tann-
hauser" through WJZ to the radio telephone audience. Mme. Gadski began her musical educa-
tion at the age of seven, had her first public appearance at ten, made her debut in opera at the
age of sixteen, and later enjoyed a continuous engagement for twenty-three consecutiv
with the Metropolitan Opera Co. of New York.
We have learned something about continuous waves
in a former chapter. Such an arc transmitter,
therefore, sends out waves that never stop, not even
for the smallest fraction of a second. By means of
the microphone into which we talk, we super-impose
upon the continuous waves the voice currents which
are, therefore, carried along by those waves.
Hence, the continuous wave in radio telephony is
often spoken of as the carrier wave, because it car-
ries the speech waves with it. This is shown in Fig.
107, schematically where the speech waves will be
seen carried along with the continuous waves, which
are emanating from the oscillating circuit.
The advent of the vacuum tube changed the en-
tire aspect of radio telephony. In the Poulsen
method as well as for radio telephone systems, it
was necessary to employ a microphone, which in
this case had to handle very large currents, some-
times as high as ten amperes. It was almost impos-
sible to design a microphone or transmitter that
would absorb such an excessive amount of energy,
166 RADIO FOR ALL
and for that reason the modulation at the transmit-
ting station was nearly always faulty, and the re-
ceived speech, music or other entertainment was as
a rule poor. Often the microphone failed to
work, and then, of course nothing came through
the air at all. At the present time, however, we are
not dependent upon power microphones, for the
reason that we now make use of the vacuum tube.
Even the simplest telephone transmitter such as
used on your house telephone can be used in the
modern radio telephone, and the main reason is that
the vacuum tube sender acts as a valve, which ampli-
fies many thousand times the voice current, sending
it out over the aerial without having a strong current
passing through the microphone.
The simplest radio telephone is shown in Fig.
108. This comprises a transmitter, a few batteries,
a vacuum tube and the usual serial and ground. The
RADIO TELEPHONY 167
diagram is shown fully in our illustration, Fig. 104.
By means of this arrangement, when we talk into
the transmitter, the oscillations generated by the va-
cuum tube are varied in amplitude. These high
frequency radio currents are continuous as well, so
that we are sending out or transmitting a continuous
wave. When words are now spoken into the trans-
mitter the voice currents are superimposed upon
the continuous waves, and at the receiving station,
the words will be heard. The outfit, as shown in
this illustration, is of course, only good for a short
range because not much power is used, and it will,
therefore, not cover more than a few miles. The
principle, however, is the same as that used in our
large broadcasting station, as we will see further on.
The system which we have just explained is the
one which is used universally today, as it has been
found that by the use of the vacuum tubes almost
any amount of power can be radiated from the trans-
mitting antenna. Usually a radio telephone sta-
tion is rated according to the amount of power it
radiates from its transmitting serial. This amount
of power, of course, varies for the different stations.
The more power we put into the serial, the further
we can transmit.
The prime reason why we can hear spark sta-
tions much further than radio telephone stations,
lies in the reason that in the former many kilowatts
are used, sometimes as high as a thousand kilowatts,
as for instance, in the great trans- Atlantic stations.
168 RADIO FOR ALL
Of course, not all this power leaves the serial, but
a fair proportion of it does. In radio telephony,
however, not such a vast amount of energy is used,
and most broadcasting stations do not operate on
more than 500 watts, which, compared to a spark
station is an insignificant amount of power. This
is one of the reasons why broadcasting stations
cannot be heard at such great distances as
Radio broadcasting, contrary to public opinion,
is not at all a new thing. Many claims are being
made as to who was the original inventor of broad-
casting, and when everything is said and done, it
probably settles down to the man who sent out the
first radio telephone intelligence. That man was
probably Reginald Fessenden, who, as far as is
known was the first and real inventor of radio tele-
phony. Back in 1906, he operated a radio tele-
phone transmitting station which was heard by thou-
sands of radio professionals as well as amateurs.
That advent marked the first broadcasting. Of
course, this was not broadcasting as we understand
the term today. By modern broadcasting is under-
stood a radio intelligence that is sent out at a certain
pre-determined schedule or program. Such broad-
casting probably did not come about until 1920.
when the Westinghouse Company transmitted the
1920 election returns from the East Pittsburgh sta-
tion, and followed this with daily concerts and other
RADIO TELEPHONY 169
entertainment which has remained to this day.
The country at large, however, did not become much
interested until the latter part of 1921, when the
Newark, N. J. Westinghouse station began to
broadcast a daily program. The newspapers were
not slow in taking up the new art, and one of
Newark's leading newspapers was the first of the
newspapers in the country to have a regular radio
section in their Sunday edition. This attracted
many readers, who before had not known much
about radio, and to whom radio had been a
Newark, N. J. became the first radio center of
the country, and soon people were storming the elec-
trical and radio supply stores in order to buy instru-
ments with which to receive radio entertainments.
New York soon followed suit, the New York Globe
being the first daily newspaper to carry a daily radio
department, informing the public as to the wonders
of radio, and how it was possible for everyone to
catch music from the air at a trifling cost. Soon
other New York papers copied the idea, and in less
than a month, there was hardly a city in the United
States within fifty miles of a broadcasting stations
that did not boast of its radio page or department.
All this tremendous publicity had its effect upon
the public who began to storm the stores and clamor
for radio goods until in January and February,
1922, the radio boom had reached a situation that
can only be compared to the oil rush of the Texas
170 RADIO FOR ALL
oil fields. The country had suddenly gone wild
over radio, and every one wanted to have an outfit to
listen in to the fascinating entertainment.
So far for the history of broadcasting. Tech-
nically, the art of broadcasting was partially de-
A- Microphone; B- Dry cells ; C- Audio frequency amplifying
transformer; D- ChoKe coil; E- Radio frequency choke coil;
F- Tuning inductance; G- Voice amplifier; H- Modulator, J-
Oscillator; K- Grid condenser ;*L- Variable condenser; M-
Grid leaK; N- Plate battery; 0- Storage battery;.
scribed in the preceding chapter. At the modern
broadcasting station, the arrangement as shown in
Fig. 109 is made use of. Here, we first have the
microphone into which the performer sings or
speaks, and a small transformer to step up voice
currents. Next, we have the voice amplifier where
the voice currents are stepped up and from thence
RADIO TELEPHONY 171
pass into a second transformer. From there the
currents pass through the so-called modulator tube,
and from there through several coils into the next
tube called the oscillator. Then the current passes
out into the antenna circuit. Of course, all this is
much more complicated, and it is not within the
limits of this volume to delve into all the technical-
ities of this circuit. Suffice it to say that by means
of this arrangement, almost any amount of energy
may be radiated out into space.
Of course, it goes without saying that the trans-
mitting tubes used for transmitting broadcast
entertainment are not the small vacuum tubes with
which we are familiar, because these could not han-
dle the energy. Instead, the tubes used are big
fellows, a foot or so high and 6 to 10 inches in dia-
meter. Such tubes of which an entire battery is
used, are built to carry large amounts of current,
and as a result become pretty hot. For that rea-
son, they are cooled by means of fans or other cir-
culating air methods. Even so the tubes do not
last forever, and occasionally burn out. If this
happens in the midst of an entertainment, which is
unfortunate, a new tube must be replaced and the
performer as a rule must go over the ground again,
after the radio audience has been informed of
At the broadcasting station, it is always neces-
sary to have a complete personnel which often com-
prises as many as twenty people. There are two
in RADIO FOR ALL
distinct parts in the up-to-date broadcasting sta-
tion. First, the studio, and second the transmit-
ting station proper. At the latter we have several
engineers who attend to the operation of the tubes,
and who are informed by telephone from the studio,
whenever the artist is ready to sing or perform. The
current is then switched on, the tubes begin to glow
and the station now transmits continuous waves.
These continuous waves cannot be heard at the re-
ceiving station, except at times, when we employ a
regenerative receiver. As soon as this receiver
gives its characteristic whistling note, we can tell
the broadcasting station has started its power, al-
though the performance has not begun.
Let us now enter the broadcasting station studio.
We assume that an opera singer is getting ready to
sing, while the accompanist is at the piano. The
attendant first announces the singer, and cautions
the performers not to make any noise whatsoever,
because any unnecessary noises such as coughing or
talking, will be heard by the radio audience. These
sounds are picked up by the sensitive transmitter.
In order to dim the echoes in the studio, its walls
are always covered with draperies which do away
with all sound reflections, echoes and the like. After
the introduction by the announcer, the performer
steps up to the transmitter, which is usually a form
of telephone transmitter attached to a large vibrat-
ing disc and looks somewhat like a small bowl. The
performer is cautioned never to stand nearer than a
RADIO TELEPHONY 173
foot or so before the transmitter when singing.
Behind the piano there is usually some sort of horn
which picks up the sounds and conveys them to a
microphone attached to the small opening of the
horn. This catches the sounds from the piano, to be
sent to the transmitting station. Of course, the
microphone transmitter wires coming from the
piano as well as those from the performer are con-
nected together, so that the sounds are picked up
simultaneously and guided to the radio transmitter.
That is why in the receiver we hear the piano and
performer's voice at the same time. To be sure,
there are certain refinements at every broadcasting
station in order to transmit the music or other enter-
Several microphones are used, for instance, when
a band is playing. A totally different arrangement
is used when a violinist is performing. In the latter
case a very sensitive microphonic arrangement must
be used, otherwise we would hear nothing of the
music, which is not unduly loud anyway. On the
other hand, when phonographic music is transmit-
ted, there is a phonograph-microphone attachment,
which is attached direct to the tone-arm of the
phonograph, and we, therefore, hear transmitted
phonograph music, the same as if we were in the
room with the phonograph.
Several of our photographic illustrations shown
in this book depict the various methods used
174 RADIO FOB, ALL
in broadcasting music from a modern broad-
We are of course only at the beginning of broad-
casting. What its future will be is difficult to state,
as is always the case with a new art.
At the present time there is a distinct and very
important use for broadcasted entertainment. A
broadcasting station now-a-days sends out news,
music, which may be vocal, instrumental, or any
other form. We also have stock quotations,
weather forecasts, children's stories, lectures and
even complete musical shows or operas have been
broadcasted lately. Entire vaudeville programs that
lend themselves to the purpose can thus be broad-
casted. A distinct field of usefulness lies in the
possibility of the radio telephone for political
speeches. There is talk at Washington at the pres-
ent time that Congress will install a powerful broad-
casting station at the Capitol whereby the President
or other politicians may broadcast their speeches so
that every one in the country may hear. This is
a tremendous possibility.
Then we have perhaps a more important feature
of broadcasting, and that is educational programs.
The day is not far off when every university will
have its broadcasting station whereby special
courses that lend themselves for the purpose will be
broadcasted so that everyone who cares to may hear
and absorb the knowledge given by our professors.
One of the surprising uses of broadcasting is that
RADIO TELEPHONY 175
it is possible today to make actual phonograph re-
cords from broadcasted music. There are now on the
market attachments which can be placed upon your
phonograph. Then by attaching a loud talking re-
ceiver to the tone-arm, it is possible to take down any
form of entertainment on a wax or zinc disc, which
can be put away for future use. Imagine that a
great opera singer is sending out one of her arias
right at the opera during a regular performance.
All we have to do is to record her voice, thereby
making our own phonograph records, and this to-
day may be done without any further trouble. Then
if we wish to hear the artist again, all we have to do
is to place our wax or zinc record upon the turning
table, and we can listen to the artist at will a month
or a year later.
It is even possible today to have an entire opera
broadcasted, moving pictures and radio music, all
at the same time. This scheme was originated by
the author in 1919 and is as follows: ( See Fig. 110.)
A recent newspaper report from Chicago brought the not at all
surprising news that grand opera music had been transmitted by
wireless telephone for over one hundred miles. Sensitive microphones
placed on the stage of the opera house caught the sound waves; the
impulses then being stepped up in the usual manner by means of a
transformer were led into an amplifying vacuum tube. Here the cur-
rent was impressed upon the radio telephone transmitter in successive
stages and then sent out over the aerial on top of the opera house.
Wireless amateurs all about the surrounding country were thus able
for the first time to hear grand opera. While this was only an experi-
ment, grand opera by wireless will soon be an accomplished fact.
During the next few years it will be a common enough experience
for an amateur to pick up his receivers between eight and eleven
o'clock in the evening and listen not only to the voice of such stars as
176 RADIO TELEPHONY
Scotti, Tetrazzini, Mac Cormick and others, but also to the orchestra
music as well, which is picked up by the sensitive transmitter along
with the voices of the stars. The surprising thing is that it is not
being done now.
This probably is due to the fact that as yet no means has
been found to reimburse the opera companies for allowing everyone to
listen in. While of course listening to the music is not as satisfying
as witnessing the performance in person, still many music enthusiasts
would rather stay home listening to the music alone than to witness
the performance itself. To your true, dyed-in-the-wool opera fiend
the performance is of secondary importance, the music always
But we must give a thought to the management, which cannot sub-
sist on an empty opera house if everyone could listen in to the actual
rendering of the opera without paying for the privilege. Needless to
say that the producers would soon find themselves bankrupt. For this
reason we cannot expect that grand opera by wireless will be an accom-
plished fact until some means has been found to reimburse the pro-
ducers, and, as every wireless man knows, this is very difficult to do.
Anyone with suitable radio apparatus can "listen in" to the music
without much trouble. No matter on what wave-length the music
would be rendered, every wireless man would find a way to listen to
it without serious inconvenience.
Probably the only logical way out would be for the management
of a grand opera company to advertise in the newspapers, stating that
no grand opera via radio would be given unless a certain amount of
revenue were guaranteed by radio subscribers before " radio per-
formances" would be given. This would mean that probably ten
out of one hundred radio stations, amateurs and otherwise would pay
monthly or yearly dues to sustain the management, which then would
not have to care how many were listening in.
This is the only practical solution. As for technical difficulties,
there are of course none. All that is necessary for the producing
company is to install a high-class wireless telephone outfit which can
be bought on the market right now and which is immediately available.
The rest is up to the wireless fraternity, which has nothing else to do
but listen in.
At the receiving end, the future up-to-date radio opera enthusiast
will of course, have a first-class receiving outfit, using vacuum tube
amplifiers, and a loud talker. Then it will be a simple matter to
listen to Scotti himself, though he be a thousand miles distant. His
voice will come out loud and distinct and the amateur's family will be
enabled to " listen in " to their heart's content.
RADIO FOR ALL 177
There is still another novel scheme recently originated by
The underlying idea is not only to give grand opera by wireless,
listen to the music and to the singers only, but to actually tee the
operatic stars on the screen as well. This is how it can be readily
accomplished by means which are available to-day, and without the
slightest technical difficulty.
Let us say, by way of example, that the opera " Aida " is filmed
in its entirety. This may mean a four or five reel feature. The opera
will be filmed just like any other photo-play.
Our large illustration shows what happens next. The stars, sing-
ers, players, the chorus, orchestra, conductor, etc., are then assembled
in a moving picture studio and in front of them is the usual screen.
The opera " Aida," which had been filmed before, t* now repeated on
the screen while the entire cast follows the screen picture closely.
Each performer, every star, every member of the chorus has his or
her own microphone in which he or she sings the regular score, watch-
ing closely the film-play as the action is unreeled on the screen. The
moving picture opera through the film operator keeps time with the
singers, and the singers themselves must keep exact time with the
performance as it is unrolled on the screen before their eyes. Inas-
much as the identical cast has been filmed, it will not be difficult for
them to keep time with their own performance, as may readily be
imagined. In other words, when Scotti sees his own figure appearing
on the screen he will know exactly how and when to sing into the
microphone in front of him.
All of the microphones go to the wireless telephone station located
in the radio room above, and there are, of course, sensitive microphones
in the studio which pick up the sounds from the orchestra as well.
All sounds are then stepped up through the usual amplifiers and are
then fed into the high power vacuum pliotrons, which finally amplify
the original sound several million times. These impulses are then sent
out over the usual aerial located on top of the house and are shot out
all over the country instantaneously.
Five hundred to 1,000 miles away and for that matter all over the
country every moving picture house will have been supplied with
the identical film at the stated performance, it having been announced
days ahead that the grand opera "Aida" will be given at such and
such an hour.
Of course, where the distances are large, the hour of rendering the
opera will vary. Thus, for instance, if Scotti were singing in New
York and a performance would start at eight o'clock in the evening,
RADIO FOR ALL
RADIO TELEPHONY 179
New York time, it would start in San Francisco at four o'clock in the
afternoon, as a matinee, due to the difference of time. Inasmuch as
such performance would probably only be held once a month, people
would not mind the inconvenience due to slight difference of time.
Every moving picture house will have its receiving apparatus with
its usual amplifiers and anywhere from six to one dozen loud talkers
scattered through the house. Exactly at the stated time the moving
picture operator will begin grinding away the opera has begun.
Simultaneously the distant orchestra will begin playing, filling the
house with music.
When the actual performance begins, it will be an easy matter for
the operator to keep time with the incoming music. All he needs to do
is to grind faster or slower, and inasmuch as Scotti with his per-
formers in New York is watching the identical film, the distant oper-
ator will have no trouble in having the music keep time with his
film. If he finds that he runs ahead for one second, he can readily
slow up the next and vice versa. With a little practice it will be easy
for the distant operator to time himself perfectly, thus giving the
patrons of his house an ideal performance.
From a financial standpoint it would be good business for the opera
company, as well as for the moving picture house, both of which would
thus derive a new income running into the hundreds of thousands with
hardly any expense whatsoever. The grand opera with an outlay
of from one thousand to three thousand dollars could buy its high
power radio telephone outfit, while every live picture house through-
out the country would be able with an expenditure of less than five
hundred dollars to buy its necessary radio telephone equipment and
this cost would only be initial, because nothing except burnt-out
vacuum tubes need be replaced and there is practically no cost
The writer confidently expects that this scheme will be in use
throughout the country very shortly.
HOW TO MAKE SIMPLE RECEIVING
IN the following pages the author has endeav-
ored to show how, with little expense, very good
radio telephone receiving outfits may be built by any
one endowed with a little mechanical ability. The
author has selected the examples with an eye to-
wards simplicity, and while these outfits are not in-
tended to be classed with those of a high efficiency
they are excellent for the beginner, and the man who
likes to "make his own."
Inasmuch as this book was written particularly
for the beginner and the novice, it was thought that
the more complicated vacuum tube sets and the con-
struction thereof should best be left out until the
reader has first gained his knowledge through the
simple crystal outfit.
It will be noted that all of the outfits here des-
cribed can be made with material usually found
about the house and in a model workshop. While a
number of outfits are shown here, it should be under-
stood that, with the exception of the vacuum tube
outfits, they are all of about the same value, all work-
ing about the same distance, and the reader is invited
to build the outfit which he likes best, and for which
he knows that he has most of the materials required
HOW TO MAKE RECEIVING OUTFITS 181
THE "SIMPLEST" RADIOPHONE RECEIVER
The important points of this set are:
( 1st ) It is simple in construction and opera-
tion. ( Mr. James Leo McLaughlin,
a New York radio amateur has actu-
ally built and operated this outfit).
A knife or razor blade and a small
nail are the only tools required to
make it. The complete set can easily
be constructed in about one-half hour.
(2nd) It is inexpensive, the total cost, in-
cluding the 'phone and antenna is less
than $3.00, the set itself costing only
2iy 2 cents.
(3rd) It is as efficient as most of the crys-
tal sets now being sold and in many
cases superior to them.
The material required is as follows :
1 Paper container (4" in diameter).
13 Paper fasteners (small size).
2 Paper fasteners (large size).
2 Oz. No. 26 enameled copper wire.
1 Small piece of silicon or galena.
1 Common pin.
Take the container (the kind used to carry liq-
uids) and punch nine holes one inch down from
the top with a small nail, one half inch apart. Into
each hole push a paper fastener. With pen and ink
number each fastener from right to left, 1 to 9.
182 RADIO FOR ALL
Alongside of hole No. 1 push two fasteners with
a paper clip underneath mark GND (ground).
One half inch down from. GND, punch a small hole ;
this is the starting point of the coil. See Fig. 111.
Take the wire and push the end through the hole.
Wrap the end around one of the fasteners GND
(on the inside of the container). Be sure that
where the wire touches the fastener, the enamel
lias been scraped off, otherwise a poor connection
Next pull the wire tight and commence winding
the coil. The total number of turns is seventy, and a
tap is taken off at each of the following turns : The
15th, 20th, 25th, 30th, 35th, 40th, 45th, 55th, and
Fig. 112 shows how to tap the coil. The im-
HOW TO MAKE RECEIVING OUTFITS 183
portant things to look out for are that the coil is
wound as tight as possible, and that the enamel is
scraped off the wire, where it makes connection
with the fasteners. The 15th turn is contact No. 1,
the 20th No. 2, etc.
The next job is the switch that moves over the
contacts. Figs. Ill and 112 show how this is made.
Take one of the large fasteners, push the ends
through the side of the cover, close to the lid. Bend
one end down flush with the side and push the other
end through the top and bend over.
Put the cover back on the container and bend
the end of the fastener so that it rides over the con-
tacts easily, when the cover is turned, but be sure
184 RADIO FOR ALL
that it touches each of them. Break off the sur-
The other larger fastener is pushed through the
lid opposite the switch and is bent, as shown in Fig.
Ill, so that it can hold the small crystal. A short
piece of bare wire (about No. 24 will do) , acts as the
cat-whisker, a pin is fastened to one end and the
other end is wrapped around the end of the switch
the part that is bent over (see Fig. 112) .
Fig. 112 shows the diagram of connections and
needs little comment.
The telephone receiver is a single Murdock or
"Rico" without head band, and can be purchased
for about $2.00. Of course any other kind may
For the antenna one-half pound of No. 18 bare
copper wire will do. This will give about 100 feet
of wire. Two porcelain cleats will also be required
and should not cost over 5 cents. The wire can be
had for about 30 cents.
String the wire the greatest length possible and
attach outer end to a tree or other elevation, at least
30 feet high (see Fig. 112). The other end of
the wire enters the house and is attached to the
switch button marked ANT; a short piece of
rubber tubing should be slipped over the wire where
it passes through the wall of the building.
A good ground may be had by connecting a wire
to the nearest water pipe. Scrape the pipe for a
length of about two inches, so that it shines,
HOW TO MAKE RECEIVING OUTFITS 185
then wrap several turns of wire around it
and twist tightly. It is, however, better to use a
To operate the set, bend the catwhisker wire so
that the pin rests on the crystal. Move the pin over
the surface until a signal is heard; at the same time
move the switch over the contacts, and leave it on
the one that brings the station the loudest.
With this set in New York City, using only a
single No. 24 wire, 25 feet long strung up in a room,
WDY's and WJZ's concerts came in fine, and on
several occasions, the phone could be held about six
inches from the ear, and still the music and voice
could be distinguished.
A SIMPLE RADIOPHONE RECEIVER
The radio receiver shown in the accompanying
drawings (Fig. 113), was designed to tune to 600
meters, using a single- wire serial about 130 feet long.
This coil has an inductance of about 537,600 cms.
and with an serial having a capacity of .0003 mfd.,
will tune to about 750 meters. A loading coil may
be used to increase the wave length if desired.
The only tools required to make this receiver are
a sharp knife, a screw driver and a pair of pliers.
A one-pound coil of No. 18 annunciator wire,
obtainable at any electrical supply store, will be re-
quired for the serial and ground. A pound of this
wire will contain about 155 feet. Cut off 20
feet for the ground connection and use the rest for
the serial. The location of the station will deter-
RADIO FOR ALL
Tuning coil .
78 turns of *24
About. 005' thicK
Cut from 3"X3'
of Tuning Coil
mine how the agrial is erected. Have it as high up
as possible, but it will give good results if it is
HOW TO MAKE RECEIVING OUTFITS 187
only 20 feet above the earth. For insulators use
porcelain cleats like those used for electric light
wiring ; if none of these are at hand, blocks of wood
boiled in paraffin will do very well. The ground
lead does not require insulation. Make ground
connection to a water pipe if possible. Gas pipes
or steam radiators may be used, but as a rule are
not as good as water pipes. Be sure both pipe and
wire are clean and bright when connection is made.
For the best results all connections should
Obtain a cardboard box or mailing tube about
3 l /4 inches in diameter and cut it so that it is 3 5/16
inches long. Civil engineers and architects get
their tracing cloth in thick- walled mailing tubes that
make ideal coil winding forms. If you don't hap-
pen to have a round cardboard box of this size about
the house, visit your city engineer. Mark a line
around the tube 5/16 of an inch from one end. With
the small blade of a penknife make 19 holes on this
line spaced 7/16 of an inch apart; these holes are for
the contact points which are the common paper
fasteners. Insert paper fasteners in holes but do
not spread points.
The coil is wound with No. 24 single cotton cov-
ered magnet wire and ]/$ Ib. will be required. To
wind the coil fasten one end of the wire to the first
paper fastener. In doing this scrape the end of the
wire, also the under part of the fastener, so that
188 RADIO FOR ALL
when the points are spread and the fastener pinched
with the pliers a good contact will be made. Di-
rectly under the first fastener and 15/16 of an inch
from end of tube insert a pin. Bring the wire down
from the first fastener, around the pin and make one
turn around the tube. Insert another pin under
the second fastener, bend the wire around the se-
cond pin, up around the second fastener, back
around the pin and complete another turn around
the tube. Repeat this for the first six fasteners.
After passing wire around the sixth fastener and
pin, wind six turns and take off another tap; con-
tinue in this manner to end of coil taking off tap
every sixth turn. When completed the coil should
have 12 six-turn taps and 6 one-turn taps, or 78
turns in all.
It is not necessary to scrape the wire where it
passes around the contact points until the coil is
wound. After completing the winding, wind a
cord around the top of the coil to hold taps in place,
remove fasteners one at a time and scrape wire and
fastener, replace and pinch with pliers. Remove
cord and give winding light coat of shellac. After
shellac is dry remove pins and winding is complete.
It is best to keep shellac away from the contact
points as it is apt to cause a poor contact between
point and wire. If the maker has a soldering outfit,
by all means solder wire to points, but if both are
carefully scraped a good electrical connection will
HOW TO MAKE RECEIVING OUTFITS 189
At a stationery store purchase four window
hooks, (paper clips). Two of these are used to
make the detector and the other two with the long
end cut off are used as clips to vary the inductance
as shown in the drawing; the general arrange-
ment of the detector is also shown. One win-
dow hook holds the crystal. The other holds a
short end of a pencil with a rubber eraser. The cat-
whisker wire is stuck through the eraser and allowed
to project about an inch. The other end of the wire
is looped a few times around the pencil and fastened
to the window hook. By rotating the pencil the
catwhisker wire can be made to touch the crystal.
If galena is used, a copper wire of about No. 30
B & S gage should be used. Galena requires a
very light contact. The two hooks that form the
detector are fastened to the wood base with small
wood screws. One end of the crystal-holding hook
is bent in a loop to hold the telephone wire terminals.
If ordinary insulated wire is used to connect the
telephone the ends may be secured under screw
heads. One of the long ends cut from the hook
used to vary the inductance forms the other tele-
phone terminal. Purchase galena at a radio store.
The telephone receiver must be of at least 1,000
ohms resistance and should be purchased from
some reliable radio shop.
A condenser shunted across the telephone is not
absolutely necessary, but they are easy to make and
improve the working of the receiver. Purchase a
190 RADIO FOR ALL
mica stove window size 3X3 and cut from it a circle
2% inches in diameter. From a piece of tinfoil cut
two circles 2 y 2 inches in diameter with a tongue %
of an inch wide and 1 inch long. Hold the tinfoil
pieces by the tongues and dip them in melted paraf-
fin, be careful not to get any paraffin on the
tongues. Lay one of the pieces of tinfoil on the mica
circle as shown on the drawing. Warm a flat iron
so it will just melt the paraffin and turn it face up.
Lay the mica on flat iron with the tinfoil up and as
the wax melts you must smooth the foil until it
makes good contact with the mica. Fasten the other
piece of foil on the other side of the mica in the same
manner. Give the base a light coat of shellac and
when it is still a bit sticky lay the condenser in place
and smooth it down.
Connect up the apparatus as shown in the dia-
gram, taking particular care that all electrical con-
nections are clean and bright. Place the crystal
in place and rotate the pencil until the catwhisker
touches the crystal. You will have to move the cat-
whisker about until you find the most sensitive spot.
The usual method of testing the adjustment of
crystal detectors is to connect up a buzzer and push
button with one or two cells of dry battery. One
binding post of the buzzer is grounded. When de-
tector is adjusted properly you will hear the sound
of buzzer in phones. If your house is equipped
with an electric door bell, have some member of the
family push the button while you adjust the de-
HOW TO MAKE RECEIVING OUTFITS 191
Receiving tronsf. /
Camera carrying case
for MS. 2 Brownie, made
to open on the side.
tector. Having adjusted the detector move clips
about until you hear signals. It is well to avoid
192 RADIO FOR AJLL
handling crystal with the fingers, and if your crystal
gets greasy from the fingers, it may be washed with
carbon disulphide (carbona) or alcohol. Mr. H.
L. Jones set up and operated this simple set with
A POCKET SIZE RECEIVING SET
This is a description with drawings of a small
pocket receiving set which the author constructed
some time ago. He, as well as Mr. Joseph E.
Aiken, obtained remarkable results with this set,
considering that it is small enough to slip in a
coat pocket. It measures about 4" X 6" X 2".
Connected to a single- wire aerial 140 feet long
and 40 feet high, in southern Illinois, Arlington
(NAA) came in clearly enough to be copied
through considerable static. Key West (NAR)
and a large number of ships and stations on the
Atlantic coast have also been received. It has a
maximum wave length of 3,500 meters.
The set is mounted in a small leather-covered
camera carrying case, with shoulder strap (No. 2
Folding "Brownie"), which has been arranged to
open on the side. ( See Fig. 114) .
The secondary coil is wound upon a wooden
form 2% inches in diameter and is about an inch
wide. After the secondary is removed and wound
with tape, the primary is wound on top of the sec-
ondary, and then the two are wrapped together.
The primary winding has 342 turns of No. 24
S.C.C. wire. Every other turn of the first 18
HOW TO MAKE RECEIVING OUTFITS 193
is brought out by leads to a nine-point switch. The
remainder is tapped every 18 turns and each
tap is connected to a point of an 18-point
primary switch. This method allows fine tuning.
The secondary coil has 400 turns of No. 28
S.C.C. wire, divided into 10 equal sections, which
are connected to the ten-point secondary switch.
A fixed condenser to connect across the phones
is made from two sheets of tinfoil, 2"X6", which are
separated by waxed paper and folded into a
The detector is shown in the diagram and is of
the catwhisker type, using galena.
Binding posts for serial, ground and phones, are
provided. A very small watch-case buzzer, and the
smallest size two-cell flashlight battery, are included
with which to adjust the detector. A small push
button to control the buzzer is mounted on the panel.
The panel on which the switches and detector
are mounted is made of Spanish cedar taken from a
cigar box and highly finished in mahogany. The
panel is mounted so that the switch knobs will not
touch the lid when it is fastened.
ANOTHER LOW-PRICED RECEIVING SET
The one sure way of making a convert to the
wireless art is to have him "listen in" long enough to
realize that the whole world is waiting to talk to him,
and then lead him to the work bench. Doubtless
there are thousands of lads who look wistfully at the
supply catalogs but get no further, feeling that the
194 RADIO FOR ALL
cost is beyond their scant means or that their elec-
trical and mechanical knowledge is insufficient to
cope with the construction of the various condensers,
coils and detectors so beautifully pictured.
The receiving set illustrated was planned for
just these boys, the item of expense and the diffi-
culties of construction having been eliminated. It
was made complete in one evening with time to
spare. It was designed to get the boys started in a
practical way, however small, because any boy, who
is a real boy, who receives a message on apparatus of
his own construction will no longer be immune to
the radio bacillus. He may throw the set away in
a month and start after an audion, but it has served
its purpose in making a convert.
In almost every community, there is one or more
good amateur station operating on 200 meters or
less, and to receive them is such a simple matter
that the beginner would never suspect it after seeing
the usual array of equipment used. One need not
be deterred by the thought of putting up an
elaborate serial on poles a single wire run from
the chimney to the garage, or a large loop in the
attic will answer every purpose.
The first thing to do is to get a piece of dry %
inch board, 4 or 5 inches wide and 6 or 7 inches long,
the exact dimensions being unimportant. Boil it in
paraffin, and on the underside press on a piece of
paraffined paper about 4 // X5 // . On this, build the
fixed condenser, which consists in all, of three sheets
HOW TO MAKE RECEIVING OUTFITS 195
of tinfoil about two by three inches, with thin paraf-
fined paper between and a heavy protective piece
on top. Connections to the tinfoil may be readily
made by means of a small screw and a washer at each
end. (See Fig. 115). Fasten a small block at
each corner, so that when the board is turned right
side up, the condenser will not rub on the bench.
Or you can make the base in one piece as shown
in illustration :
The variable condenser is arranged as follows:
First press down a piece of paraffined paper and
then a sheet of smooth tinfoil on top of this, working
out all the wrinkles and bringing the left-hand edge
around over the side of the board so that connection
may be easily made therewith. The tinfoil should
196 RADIO FOR ALL
contain an area of from 15 to 25 square inches, de-
pending upon how thin the paper is between the
plates. The upper plate consists of a smooth piece
of heavy tin or brass, the corners and edges of which
have been smoothed off. This is to be fastened
down with two screws and is slightly bent down so
that the free edge will stand about a quarter of an
inch from the tinfoil. Cut the latter away for about
a quarter of an inch from around the screw holes
and coat with shellac. Cover with a piece of 1/16
inch fibre which serves as a spacer, and press
flat. Screw down the tin plate, and provide a screw
adjustment so that the distance between the plate
and the tinfoil may be altered as desired.
The tuning coil in the usual set is here replaced
with a small coil consisting of 50 feet or less of
magnet wire. The capacity of the condenser being
unknown, no definite data can be given for this;
but it is a very simple matter to make a few tests.
Take any odd length of magnet wire, say number
22 or 24, and wind it on a cardboard about an inch
and a half in diameter, and the chances are that it
will work. If the signals keep increasing in strength
as the condenser is screwed down, it means that
more turns should be added to the coil. If the sig-
nals are loudest when the condenser is wide open,
it is probable that too many turns are being used.
The capacity of the condenser itself may be reduced
considerably by placing another sheet of paper be-
tween the plate and the tinfoil.
HOW TO MAKE RECEIVING OUTFITS 197
We have now only to construct the detector, and
here more than on any other feature depends the
strength of the signals. Do not use a large crystal ;
break it up into pieces not more than an eighth or
a quarter of an inch and then test a dozen or more
pieces until a sensitive face is found. To do this
the crystal does not have to be mounted. Simply
put it on any clean metal surface and carefully go
over each with a whisker wire, which may be easily
handled by sticking it in the end of a piece of wood.
A test buzzer will be necessary, and, of course, con-
nections must be made in the usual manner. When
a good crystal is found, solder a brass nut or a short
piece of tubing to a piece of sheet brass and fasten
to the base, after which pack in the piece of galena
The essential requirement in a crystal detector
for a beginner is to have it so arranged that the en-
tire surface of the crystal may be explored quickly.
So many detectors have the whisker wire on
the end of a screw and are almost worthless because
a sensitive spot is no sooner found than lost, due to
a slight wobble of the whisker caused by turning the
screw further to adjust the tension. If the whisker
is about 24 f an mc h l n g the pressure is relatively
unimportant when it has once been placed on the
right point. In the design illustrated, a binding post
is mounted on a block with a single head screw which
is set in only fairly tightly in order that the shank
198 RADIO FOR ALL
may be moved to or from the crystal. The cat-
whisker wire is best soldered to the shank.
Four binding posts two for the phones, one
for the serial and one for the ground complete
As previously mentioned, the cost is small, not
exceeding 25 cents for all needed parts. The tun-
ing is done entirely by the condenser.
It works surprisingly well.
A $1.00 RADIO SET
The broadcasting of radiophone concerts has
been given a wide publicity in the magazines, as well
as in the daily press, and many people who never
before had read any details about Radio and its
possibilities, have become interested in it, and would
like to know how these concerts may be received.
Most of those who do not know anything about
Radio are struck, when opening a Radio magazine,
by the variety of equipment advertised, and espe-
cially by the prices quoted; some of them then
become discouraged and do not push further the
idea of buying a receiving set.
For these persons we shall give in this article
a little practical data for making a home-made re-
ceiving apparatus, which will cost about $1. Of
course, the efficiency and sensitivity of such a set
cannot be compared to the modern types of receiv-
ers which are now obtainable, and in which vacuum
tube detectors and amplifiers are used, but very
good results may be had with such a cheap outfit,
HOW TO MAKE RECEIVING OUTFITS 199
provided the directions given in this article are care-
To build this small receiver, the main things
to secure are a good telephone receiver, which may
be bought very cheaply in a second-hand shop, and
a mounted crystal of galena, that is, a piece of ga-
lena inserted in a little block of lead; this may be
bought at any Radio supply house for a few cents.
Or else a 50 cent "Rasco" Detector will do.
The home-made detector may be built very sim-
ply, as shown in the sketch, Fig. 116 A. Two nails
should be driven into a piece of wood used as a base
and the mounted crystal tightly secured to one of
the nails by a tight winding of copper wire fixed
around both. The exploring wire, better known
among amateurs as the "catwhisker" consists of a
piece of the same wire wound around the other nail,
as shown, and bent so that its tip lies down on the
crystal with a certain pressure ; this end of the wire
should be sharpened with a nail file, so that the tip
is about as sharp as a pin. About 2 inches of the
wire from both nails should be left out to make con-
nections with the outside circuit.
The antenna to be used with such a receiving set
may be of several types, according to the space
available for the erection of the wires, which com-
pose it. If in the open, the simplest type of antenna
to erect is a single wire about 150 feet long,
attached as high as possible between trees, houses or
RADIO FOR ALL
Piece of wood-
No. 20 wire
2 Turns between each noil
DETAIL OF TAPS
/ 6 turns-
/ 4 turns *T 4
2 turns '
DETAILS OF WINDING
OF THE TUNING COIL.
To aerial F
other natural supports which may be at hand; at
each end of the wire, an insulator should be fixed,
HOW TO MAKE RECEIVING OUTFITS 201
and may consist of a piece of dry wood about 10
inches long, preferably, or two porcelain cleats.
These insulators are then inserted between the
string fixed to a nail and the wire itself, as shown
in Fig. 116 B.
Almost any kind of wire may be used for an an-
tenna and either insulated, bare, or enameled wires
are quite suitable, provided they are strong enough
not to break when stretched; No. 18 or 20 B.S. is
quite suitable. If the set is to be installed indoors,
the wire should be well insulated where it enters the
house and it would be advisable to use a piece of
rubber covered cable as employed in motor cars to
connect the spark plugs.
If in a town or other place where it is not possi-
ble to stretch a long wire between trees or poles, a
greater number of shorter wires may be used, but it
should be remembered that the higher these wires
are erected, the better. If only a small surface,
such as a roof, is available for the installation of the
antenna, four or five wires parallel to each other and
about two to four feet apart will make a good
antenna. They should all be connected together at
one end and the connections soldered, if possible;
from this end the "lead-in," that is the wire carrying
the current to the instruments, comes down into the
house. See Fig. 116 B.
Another case is that if it is impossible for one
reason or another to install an outside antenna, an
indoor one may be rigged up and may be of the same
202 RADIO FOR ALL
type as the last one described. Of course, the effi-
ciency of such an antenna is very poor with a crystal
receiver, but some results may be obtained if the
receiver is not more than three or four miles from
some transmitting stations. With an indoor serial
composed of four wires 35 feet long and using the
inductance described in this article, the author
received the Radiophone transmission from WJZ
eight miles away.
The ideal ground connection is a large surface
of zinc or copper plates buried in damp ground,
about two to three feet deep. Another good ground
may be made with long wires buried in the same way.
These grounds are only possible for the fellow in the
country, but for the city dweller, the only possible
grounds are the water pipe or the radiator system.
In any case, the preference should be given to the
water pipe, but if it is impossible to reach it with
a rather short connection, the radiator should be
used. The pipe should be scraped to insure a good
contact and the connections soldered if possible.
The best is a ground clamp.
How IT WORKS
Once your detector is made and your antenna
erected, with your ground wire fixed to a pipe, all
that it is necessary to do, is to listen in the receiver
while adjusting the detector. This adjustment
merely consists in moving the sharp point touching
HOW TO MAKE RECEIVING OUTFITS 203
the crystal until some signals are heard. If in a
city, or in the neighborhood of transmitting sta-
tions, some signals almost certainly will be heard
with the first attempt, provided the crystal of galena
is a sensitive one.
With such an outfit, there are no tuning possi-
bilities since no means of tuning are available and a
great improvement to the set would consist in a
tuning inductance, which may be made as explained
hereafter. This inductance is not indispensable
and spark signals as well as radio telephony were
heard by Mr. Robert E. Lacault with the detector
alone, but in many cases the intensity of the sig-
nal will be increased many fold by the use of such
a "tuning coil/'
CONSTRUCTION OF A SIMPLE TUNER
Fig. 116 C shows a type of home-made induc-
tance, which can be contructed very cheaply. It
consists of a piece of wood forming the base, and 20
brass nails about 1 y 2 or 2 inches long, driven into the
board in a circle, as shown in Fig. 116 D. To wind
the inductance, about 265 feet of No. 24 or No. 26
double cotton covered wire, is necessary. The be-
ginning of the winding should start at one of the
nails, as shown in Fig. 116 C-D, the wire, which
should be scraped of its insulation, should be twisted
around the nail to make contact, and fastened.
Thejn, two turns around the circle formed by the
nails should be wound and the wire fixed to the next
204 RADIO FOR ALL
nail, No. 2, as shown in Fig. 116 E. Twenty turns
should be wound in the same manner with contacts
every two turns made to the first row of 10 nails,
numbered 1 to 10. From the nail No. 11, 20 turns
should be wound before a contact is made on the
Nail No. 12 and thereafter the same number of
turns should be wound between each step.
This will form a total inductance of 200 turns
and almost any number of turns may be inserted in
the circuit by connecting the necessary sections of
20 and 2 turns between the antenna and ground
clips. These clips making contact on the nails and
shown in Fig. 116 E, are ordinary paper clips and
make very good contacts on the nails. The diagram
of connections of the complete set, including the
tuning inductance, is shown in Fig. 116 F.
To tune the set when signals are heard in the
telephone, the clip making contact with the nails
connected every 20 turns of the coil, should be va-
ried, so as to increase the intensity of the signals;
then, a fine adjustment is obtained by changing the
position of the other clip which varies the number
of turns in the circuit only two at a time.
This little set, which is easy to build, will provide
a lot of entertainment to those interested in Radio
and if near enough to a Radiophone broadcasting
station, the voice will be heard quite clearly.
AN EFFICIENT JUNIOR RECEIVER
Today in almost any magazine you chance to
pick up it is possible to find the advertisements of
HOW TO MAKE RECEIVING OUTFITS 205
junior receivers of some kind. Most of these are
nothing more than a tuning coil and detector
mounted in some kind of box or cabinet. These are
easily made and are quite efficient on short waves for
some distances. This is the reason the author is des-
cribing the junior receiving set he constructed of
material taken from old apparatus. Yours may be
of old material or of material bought for the purpose.
To begin with, a cabinet is constructed to the
inside dimensions of 6 by 9 inches, by 6 inches in
depth, Fig. 117. The material the author used
was birch one-quarter inch thick. It is put to-
gether with small screws and glue. When the glue
has set it is stained a mahogany color and varnished.
This coat is allowed to set for three days and is then
rubbed down with pumice and water, then varnished
again. If this is done carefully, you will have a
cabinet closely resembling a factory product.
The front panel is of bakelite or formica one-
quarter inch thick and cut six inches wide and nine
inches long. Before drilling, a template of the front
panel is made of heavy paper and the location of the
instruments are figured out and marked on this, so
as to reduce the chances of mistakes. The template
is then laid over the panel and the transferring is
done with some sharp pointed tool. The drilling of
the holes for the panel mounting screws, the switches
and switch points, variable condenser and detector
is accomplished with some small sharp drill. The
panel is best attached to the box as shown in Fig.
RADIO FOR ALL
Method of fasten-
ing panel incabine"
coll to bocK
The tuning coil is of No. 24
magnet wire, wound on a
HOW TO MAKE RECEIVING OUTFITS 207
six inches long and three and one-half inches in dia-
meter, the winding is tapped at 20 equal spaces.
The switch levers, switch stops and switch points
are put on the front panel and the taps are con-
nected to the switch points and the coil is mounted
behind the panel with wooden blocks as shown in
Fig. 117 B. This completes the tuning coil and
The variable condenser is, or can be, any stan-
dard condenser having a capacity of about .0005
mf . ; the author's was a Murdock panel type having
that capacity. The condenser is mounted back of
the panel and the indicating dial is screwed on to
The detector can be of any good reliable type of
crystal (preferably galena) detector. It may be
either an old one or it may be purchased for this pur-
pose. It is taken from its base and mounted at the
top of the front panel.
A small fixed condenser having a capacity of
about .0015 mf. is used for the phone or stopping
condenser. This is screwed to the bottom of the
cabinet and is used to shunt across the phones. This,
completed, makes the set ready for work on wiring
after the binding posts are put in place as shown on
the drawing of the front panel.
Run a wire from the switch lever on your left
to the binding post at the upper right and mark this
A. The other switch is connected to the other bind-
ing post and marked G. A wire is run from the
208 RADIO FOR ALL
left side of the tuning coil winding to one of the
variable condenser terminals, then to one binding
post on the detector. From the other detector bind-
ing post a wire is run to the phone condenser and
then to the phone binding post on the left. An-
other wire is run from the other variable condenser
binding post to the right hand end of the tuning
coil winding, to the phone condenser and then the
other phone binding post. The set is now com-
pletely wired and the cabinet may be closed and
sealed as shown in Fig. 117 A.
For use the aerial is connected to the binding post
marked A and the ground to G. The phones are
connected to the binding posts on the bottom of the
panel. Most of the tuning is accomplished through
the switches, while the variable condenser is used
mainly to tune out interference. All connections
are shown in Fig. 117 D.
A PORTABLE RECEIVING SET
Herewith is described a receiving set, the con-
struction of which is somewhat radical, as it uses
no aerial of any kind. It is only in an experimental
stage, but Mr. Eugene M. Kiel has found it very
useful for short distances. A radio club or a troop
of Boy Scouts on a hike always want to keep in
touch with the nearby home station, and with this
set all that is necessary is to raise the lid and connect
the batteries; there being no serial to unfold and
hoist in the air.
The box is 10"X10"X18" over all, constructed
HOW TO MAKE RECEIVING OUTFITS 209
of l /2 inch hardwood with one side on hinges so that
it can be raised when in use, the case lying on the
other side. Brass corner-pieces and angle strips
make the case stronger and add much to its appear-
ance. It is also fitted with a handle for carrying and
a hinge hasp.
Two and a half inches from the top a l /$ inch
Bakelite panel is mounted by means of l / 2 inch
cleats. On this panel are mounted the following
instruments, as shown in Fig. 118: (1) The loop
coil which is used for an serial; (2) a variable con-
denser of .001 mf. capacity for tuning; (4) a rheo-
stat for the filament of the audion bulb. The bulb
itself (3), or, rather, the socket for the bulb, is
mounted in a recess 4 inches below the top of the
panel, as shown. Binding posts are provided for
attachment of "A" and "B" batteries and also the
telephones, for which a space is provided by the
setting of the panel below the top of the case.
The coil (1) is preferably a Litz wire- wound
coil of small distributed capacity, but not of the
honeycomb or lattice type, because the zigzag wind-
ing of the wire will not permit a directional effect.
Sixty-five turns of wire, bank-wound on a circular
wooden form 2 inches in diameter as shown, will be
about right for 200 to 400 meters wave-length.
The connections are self-explanatory, the con-
denser ( 5 ) being the grid condenser.
If desired, there is room in the case for the "B"-
battery. Any amount of wire can be wound on
the coil, to receive any wave-length desired.
RADIO FOR ALL
Front View Sectional Side View
i WAAA/ -^5"
To receive, adjust the plane of the coil in the
direction of the sending station and tune the signals
HOW TO MAKE RECEIVING OUTFITS 211
in with the variable condenser. It must be under-
stood, of course, that this set will not respond to
signals transmitted from great distances. Good
receiving depends primarily on the power of the
local transmitter as well as upon the most effective
tuning of the receiver and functioning of the
A SIMPLE AND EFFICIENT SHORT WAVE
Here is a short wave regenerative receiver
which can be constructed by the amateur very
economically. When the outfit described below is
carefully made up, it is a credit to an operating
table and is one that the most exacting of radio fans
will take great delight in showing his friends and
fellow bugs. It is easily made up, requires but very
few parts, and is so assembled that it is easily acces-
sible at all times for the changing of hook-ups. The
builder has his choice of mounting the outfit, which
is designed along the lines of the famous Paragon
short wave regenerative receiver, in cabinet form or
assembling it upon a pair of braces or brackets. It
has not been put to any extensive test, but Mr.
Frederick J. Rumford has worked on 100 to 400
meters with very good results, and the author feels
sure that the builder can get still better results by
212 RADIO FOR ALL
In making the outfit, one needs two 3-inch Bake-
lite dials engraved as shown and one 2 -inch dial also
engraved. These dials must have knobs attached
to them. Eight brass or copper binding posts, such
as are used with any radio receiving apparatus, are
also required and one complete variable switch as-
sembly with five contacts and their necessary nuts
and washers. These would look best if they were
nickel plated. The switch lever will swing within
a radius of one inch. This switch is for the purpose
of tapping the primary of the loose ( vario- ) coupler.
One of the contacts on the switch is left idle. Now
we will start on the panel and continue until the
whole outfit is ready for instant use.
Fig. 119 A shows the exterior view, or front of
the panel with the necessary articles mounted in their
respective places and the symbols indicating them.
Fig. 119 B represents the interior view, showing
the variometers and loose coupler mounted in their
places, and the method of mounting them.
Fig. 119 C shows both the internal and external
hooking-up for the outfit. The builder following
this hook-up should get very good results.
The panel may be bakelite, rubber, oak or box-
wood and should be 12 inches long, 6 inches wide
HOW TO MAKE RECEIVING OUTFITS 213
and from ^ to ^ inches thick. The measuring
and drilling for the necessary holes should be done
214 RADIO FOR ALL
first, then the panel sandpapered and given two or
three coats of varnish or paint. The panel described
was made of oak and had three coats of black, glossy
varnish. For the shafts on the variometers there
should be ^4-inch holes drilled, for the binding posts,
3/16-inch holes and for the switch contacts and
switch lever %-inch holes. After the drilling and
painting are done the panel is ready to be engraved.
The symbols should be neatly engraved on the front
of the panel with a sharp-pointed slender tool and
filled in with white india ink or a similar substance.
The panel is then ready for the mounting of the
binding posts and switch assembly.
MAKING THE COILS
We will pass to the making of the different coils
necessary for the successful operation of this outfit.
The amateur must procure six cardboard tubes in
the following sizes: two, 4 inches in outside dia-
meter and 2 inches long with a wall y% of an inch
thick ; one form, 3 inches in outside diameter and 2
inches long with a wall ^ of an inch thick; two,
2^4 inches in outside diameter and 2 inches long with
a wall y% of an inch thick ; one, 4 inches in outside
diameter and 3^ inches long with a wall y% of an
inch thick. All forms that are 5 inches in outside dia-
meter are the different primaries for the different
variometer assemblies, and the forms smaller in out-
side diameter are the secondaries. Now take the two
primaries that are 2 inches long and drill a hole in the
HOW TO MAKE RECEIVING OUTFITS 215
center of them to allow a loose fit of a }4' mc h shaft.
This shaft is the means by which the secondary is
revolved within the primary and the hole to be drill-
ed in the secondary forms should be small enough to
allow for a snug fit on the same size shaft. After
this has been done, the four coil forms should be
given a couple of coats of some good insulating com-
pound. After they have dried they are ready for
the wire to be wound upon them.
In this instance, the author used No. 24
D.C.C. magnet wire, On the primary form of the
variometer number one, the winding should start in
Y% of an inch and continue over for ^ of an inch ;
then skip a space of ]/ 2 inch and continue winding
until y% of an inch from the end. The author
thinks it advisable to have a little brass (never iron)
machine screw on both ends of each of the coils with
suitable nuts and washers to which to attach the
wire upon the starting and finishing of the winding.
It also provides means of hooking the primary and
secondary in series. This will make about 42 turns
in all on the primaries of variometers No. 1 and No.
2, making 2 1 turns to a section. Both primaries are
wound alike. As the reader will note in Fig. 119
B, the coils are all wound in two sections; the space
in the center is left to allow room for fastening the
shaft securely. After being wound, the primaries
should be given a coat of shellac but care taken
not to get too much on them as it would cause
216 RADIO FOR ALL
Now comes the making of the secondaries for
variometers No. 1 and No. 2. These coil forms are
2^4 inches in outside diameter and 2 inches long.
The winding on the coils starts y% of an inch in and
continues over for % of an inch, leaving a %-
inch space. It again continues over ^J of an inch,
leaving yfc of an inch at the end. These coils are
fastened at both ends by the same means as
used on the primaries. The secondaries should also
THE LOOSE COUPLEE
The next step is making the loose coupler. The
primary is 4 inches in outside diameter and 3j/2
inches long with a wall l /% of an inch thick. The
primary should have a lip on it as, shown in Fig.
119 B, the purpose being a means of fastening the
shaft. This coil form should be treated like the
others. After it has dried, the winding will start on
the lip end by attaching the wire upon the machine
screw or post as was mentioned above,, as was
done on the other coils. It should be wound 2
inches down with No. 24 D.C.C. magnet wire. In
fact, all the coils are wound with this size wire and
must also be wound in the same direction. After
this coil has been wound, it is ready for the shellack-
ing. On this coil four taps will be taken off. As
the two inches of winding will equal 66 turns of
wire, the taps will be taken off on the 16th, 33rd,
HOW TO MAKE RECEIVING OUTFITS 217
49th and 66th turns. A good way to take them off is
to scrape the insulation back on the wire on the above
numbered taps or turns and solder short pieces of
No. 14 bare copper wire upon the scraped section,
which will in turn connect to the different contacts
on the panel.
We are now ready to make the secondary coil
for the loose coupler. This coil form is 3 inches in
diameter and 2 inches long with a wall y% of an inch
thick. It should have a hole drilled in the center
of it to allow for the passing through of a J4 of an
inch, snug-fitting shaft. This shaft is for the pur-
pose of revolving the secondary coil within the pri-
mary coil and should be drilled for accordingly on
the primary. The winding, to be fastened the same
as in the case of the other coils, will continue over
for % of an mcn skip a space of 1 A of an inch and
continue for ^ of an inch more. This end will be
fastened upon the post fitted for it. The second-
ary is now ready for its coat of shellac.
As was said above, all the coils are wound with
No. 24 D.C.C. magnet wire. The primaries on va-
riometers No. 1 and No. 2 will have 42 turns upon
each of them, which will be 21 turns per section,
making a total of about 45 feet of wire to each pri-
mary, or 90 feet for the two. The two secondaries of
variometers one and two will have 50 turns each,
with 25 turns to a section. Each coil will take about
36 feet of wire or 72 feet for both. The loose coupler
primary has 66 turns of wire, which would equal
218 RADIO FOR ALL
about 71 feet. The loose coupler secondary has 50
turns of wire, 25 turns to a section which would
equal about 40 feet. In all, it requires 273 feet or
close to one-half pound of the wire.
ASSEMBLING THE PARTS
The outfit is now ready to be assembled. The
binding posts and switch assembly have already
been mounted. Now mount the primaries or vario-
meters No. 1 and No. 2, by four little wood screws,
two to a coil, which will screw in through the coil
form into the back of the panel, so as the shaft hole
on the coil form will come in line with the hole in the
panel. After that, get the necessary shafts, which
should be threaded their whole length. Each one
of these shafts should be 5 inches long and ^4 of an
inch in diameter. One end of the shafts should be
screwed into the knob on the dial and soldered so
that it will not work loose. It is then in turn pushed
through the panel from the front through the pri-
mary coil and nuts run on it so there will be a nut
on the front and back of the secondary at each end,
and on the inside and outside of the primary, which,
when drawn up tight to the forms, will hold them
securely. The above operation should be executed
on both variometer assemblies. In hooking the pri-
maries and secondaries in series, take pieces of No.
18 flexible lamp cord of sufficient length and con-
nect the ends of it upon the screws or posts that are
provided in the coils.
In assembling the loose coupler: There is a
HOW TO MAKE RECEIVING OUTFITS 219
rest made of 8 inches long, 4 inches wide and ^ of
an inch thick, which in turn is secured to the back
of the panel by two wood screws, which go through
the panel from the front. This rest in turn will
support the primary of the loose coupler. The pri-
mary is then mounted upon the rest and held there
by four little braces, two of them angle form and
the other two straight. These braces may be cop-
per, brass or iron. The builder must bear in mind,
that between the back of the panel and the front of
the primary coil form, there must be just three
inches of space. This is absolutely essential or
otherwise, when the secondary on variometer No. 1,
is rotated it will in turn rub against or strike the
primary on the loose coupler. After this has been
done, the secondary of the loose coupler is mounted,
the same as the secondaries on the two variometers.
The wiring for the back of the panel is done with No.
14 stiff bare copper wire, which can be bent into the
different shapes desired by the builder. Figure 119
B, shows the true method of mounting the primary
of the loose coupler. The taps on the primary are
hooked to their respective contacts on the panel.
Fig. 119 C, shows the method of hooking-up the
outfit. Any trouble the author has encountered in
the working of this receiver he has found to be due
to run down "B" batteries. There should be little
or no trouble for the amateur in building this re-
ceiver as the drawings are self-explanatory.
220 RADIO FOR ALL
PRACTICAL V. T. DETECTOR AND
The accompanying drawing, Fig. 120, shows
to good advantage a detector and two-stage ampli-
fier, which have been in use for over a year; from
this set, Mr. Frederick T. Rumford, the builder, has
obtained the very best results. He designed it for
the purpose of combining efficiency, simplicity and
compactness. It requires but very little work to
build, and its actual cost is less than $50. This price
includes the tubes, and as every amateur knows, in
the average detector two-stage amplifier sets, the
tubes are an extra expense.
Below is the list of necessary items, with their
2 " Rasco " Amplifying Transformers @ $2.65 $5.30
1 V. T. Detector tube @ 7.00 7.00
2 V. T. Amplifier tubes @ 7.00 14.00
3 Murdock V. T. sockets @ 1.00 3.00
3 Telephone jacks @ .85 2.55
2 Formica panels, 7" x 4y 3 " x %" . . . ' @ 1.50 3.00
3 Grid leaks and condensers 0.0005 mfg., 1
megohm @ .50 1.50
1 Telephone plug @ .75 .75
25" of round %" brass stock or rod .30
15" of flat brass stock %" wide i/ 8 " thick -25
5" bare copper wire B. & S. No. 8 .30
Screws and bolts .50
8 Large size binding posts @ .20 1.60
2 Rheostats for back mounting @ 2.00 4.00
Actual cost $44.05
This outfit is so compact that the builder has
often carried it from city to city in his travels.
HOW TO MAKE RECEIVING OUTFITS 221
Those who build this set can mount it in a cabinet,
if they so desire. It may be easily duplicated and
222 RADIO FOR ALL
requires but a few tools in the making, such as a
screw driver, etc. It is composed of all standard
parts, which can be readily purchased in any radio
supply store, but, no doubt, most amateurs have the
necessary parts lying around. It will take only
very little time to assemble this outfit when ready.
With the accompanying data are four drawings
Fig. 120 D shows the front panel with the differ-
ent apparatus mounted, with the correct dimensions.
Fig. 120 C side view and also the interior, show-
ing the positions of the tube, transformers, rheo-
stats and jacks.
Fig. 120 A represents the interior looking down
from the top.
Fig. 120 B represents the rear panel, showing
the different dimensions for the placing of the
binding posts and positions of the different
Fig. 120 E shows the general hook-up with pro-
We will now pass on to the actual making of
this set. The two 7"X4^"X}4" panels are given
a dull grain finish with No. sandpaper, and then
rubbed with oil. After this, the usual mark-
ing off and drilling of holes is done as shown in
Figs. 120 B and 120 D. The rheostats and jacks
are mounted on the front panel as shown and the
binding posts are next mounted on the rear panel,
which panel will be cut out at the corners, see Fig.
HOW TO MAKE RECEIVING OUTFITS 223
120 B. This gives the panel a distinctive appear-
ance and also provides for air in case the outfit is
mounted within a cabinet.
The round J^-inch brass rod is now cut into
four 6-inch lengths, being drilled and tapped at each
end to take ^-inch machine screws. If the out-
fit is not mounted in a cabinet, it would be advis-
able to have these rods nickel plated. For that
matter, it would be a good idea to have all the metal
parts that are exposed to view nickel plated, as this
will set the outfit off to its best advantage.
The eight binding posts, of which four are on
each side of the rear panel, are indicated by the
engraving upon this panel as follows : On the right
side: A is for the "A" battery, which in this parti-
cular instance is a 6-volt 60-ampere hour Eveready
storage battery; B, for the "B" battery, which hap-
pens to consist of 20 No. 703 Eveready flashlight
batteries, wired in series multiple. The reason for
this is that with three tubes functioning, the "B"
battery will not stand up very long, and it also weak-
ens the amplifying power of the outfit. There is a
jumper wire which runs from the "B" battery nega-
tive to the "A" battery negative.
Now the posts on the left-hand side are as fol-
lows: No. 1 is for the tickler connection, P, plate,
G, grid, and F, filament. As will be seen, there are
but very few binding posts, not at all like the old
amplifier sets, which had a large number of posts,
and were complicated and awkward to operate.
224 RADIO FOR ALL
All the tubes are of the same filament voltage and
the plates are of the same "B" battery voltage.
We will pass to the making of the strips for the
socket shelf. This is cut, drilled and tapped as per
Figs. 120 A and 120 C. The sockets are then plac-
ed upon the strips and held in place by means of
screws and nuts; the size is left to the individual's
The sockets are to be spaced equally apart, leav-
ing a little margin of space at each end. The as-
sembly in turn is mounted between the two panels
as in Figs. 120 A and 120 C, and held there by
means of screws, which are passed through the panel
and secured on the back by nuts. The brass rods
may now be screwed between the panels. The two
" Rasco " amplifying transformers can then be
fastened to the back of the rear panel by means
of screws and nuts, which are properly spaced, as
shown in Fig. 120 B. As mentioned, the holes
above the jacks will give the necessary ventilation
and also serve as windows so the brightness of the
tube filaments may be observed.
Now that the outfit is assembled, the next step
is the wiring, which is done with No. 8 B. & S. bare
copper wire, which it is advisable to run as straight
and direct as possible as this wire is very stiff. It
would be advisable to straighten the wire out, mak-
ing it firm and rigid.
The ingenious arrangement of the different
parts makes most of the leads comparatively short
HOW TO MAKE RECEIVING OUTFITS 225
and direct. The wiring is extremely simple. The
positive terminals of the filaments are connected to-
gether on the sockets by one wire running straight
across ; one wire runs from the negative terminal to
the front panel and across the width, having the two
rheostats connected from it onto one side of each.
The other side goes to each individual tube socket,
having one side of the amplifying transformer se-
condary connected to it. The three jacks are con-
nected on one side to the plates of each individual
tube, and on the other side, to one wire which runs
direct to the positive binding post of the "B" bat-
tery ; the two center strips of the jacks are connected
to the two individual amplifying transformer pri-
maries. The other side of the amplifying transform-
er secondaries are connected on one side of the grid
leak and grid condenser which connect directly to
the tube grids of each individual tube. The end
jack connects on one side direct to the plate of the
last amplifying tube, and the other side connects
direct to the positive side of the "B" battery.
We have omitted showing the position of the
grid leaks and grid condensers, which are combined,
but in the outfit described, the builder has secured
them to the inside of the rear panel. The maker
may use his own judgement regarding this.
The grid leaks of this outfit are 1 megohm resis-
tance and the grid condensers are of 0.0005 mfd.
capacity. They were purchased from the Radio
Specialty Co.; the jacks and plug were purchased
226 RADIO FOR ALL
from the Federal Telephone & Telegraph Co., and
the sockets from the Murdock Co. The rest of the
necessary supplies were obtained from the nearest
radio supply house. In this particular instance we
used the Magnavox Radio Telemegaphone with one
set of binding posts connected to the extra telephone
plug, and the other set connected to a 6-volt 40 am-
pere hour storage battery, which had a rheostat con-
nected in series, making various adjustments and
continuous service possible. When the amateur
wishes to use this loud speaker, he plugs into either
jack he desires and, presto, the signals will be heard
all over the room. With this arrangement, the nec-
essity of having the receivers clamped on the head
all the time will be eliminated and will make it also
possible to entertain any number of friends, when
radio music is being transmitted. No doubt, you
have noticed by this time that very little adjustment
is required in operating this outfit. After you have
adjusted the detector and the amplifier rheostats, it
is then ready for use at any time. The builder has
used " Rico " phones for the headset.
By shunting a variable condenser across the
posts marked No. 1 and F, you will obtain a regen-
erative effect, or shunting at the tickler coil which
may be a honeycomb coil across No. 1 and P and a
honeycomb coil across G and F will act as a second-
ary having the usual primary will make it possible
to tune any wave-length 100 to 20,000 meters with
the usual variable condenser to make sharp timing
HOW TO MAKE RECEIVING OUTFITS 227
possible. It will be noted that all the apparatus is
fastened to either the front or the rear panels and
almost all the connections are made direct from the
binding posts on the rear panel, making it possible
to remove the different apparatus from time to
time, whenever it is necessary to inspect them, or for
the replacing of a new V. T. or for renewing
If traveling any distance, the outfit can be eas-
ily knocked down and the different parts stowed
away in the corners of a bag or trunk. The com-
plete diagram of the proper connections is shown in
Fig. 120 E, with the proper symbols; the let-
ters and numbers are the same as on the panels them-
selves. To get the proper wiring for the backs of
the panels it would be advisable to reflect the draw-
ing in a mirror, or to place it on top of a plain piece
of paper, right side up and under this paper, have
a sheet of carbon paper, carbon side up. This last
will give the best results as the tracing of the ori-
ginal drawing will make the proper impression upon
the under side of the plain sheet of paper. This
idea would apply to any or all diagrams.
The author has covered all the necessary details
pertaining to this particular outfit, but will say a
few words more to the effect that its advantages
are neatness, fine finish, compactness, workman-
like construction, moderate price and efficiency. To
really understand and appreciate its worth, it
would be advisable to compare it with some of those
228 RADIO FOR ALL
sold in stores. The beginner can make this outfit
without the least danger of making a "bull" of it,
as all the parts are of well-known makes and widely
advertised in all the radio publications and it only
requires patience and time to assemble.
The author feels sure that all these outfits can
be built without the least difficulty, as all the draw-
ings are self-explanatory.
THE FUTURE OF RADIO
As the author has mentioned often in his various
editorials published in Modern Electrics, the Elec-
trical Experimenter, Science & Invention, as well
as Radio News, the radio business may be likened
to the amateur photographic business. Within
the next few years, we shall see every drug
store selling complete radio outfits that can
be put on top of the phonograph at home,
and which can be worked by your six year
old sister. All that is required of you is to mani-
pulate a few knobs, and from a concealed horn, the
latest j azz band music will then issue forth. To be
sure, this music is broadcasted from a central sta-
tion which may be a thousand miles away
Then too, the day of the radio newspaper is
quickly coming. Important news of the day will
be broadcasted by radio telephone daily at stated
intervals, as will be weather reports and other infor-
mation useful in every community. But of course,
the development of radio will not stop at radio tele-
phony alone. Great and wonderful things are com-
ing in radio which are undreamt of today. New
uses are constantly being found. New improve-
ments are being made almost over night. We cease
to wonder when we hear of some new marvel that is
230 RADIO FOR ALL
being performed by radio, and simply shrug our
shoulders and say "well that was predicted long
ago." Thus, recently, a physician several hundred
miles inland listened to the heart beats of
a man lying unconscious on a ship three miles out
on the ocean. Every heart beat was transmitted
clearly and faithfully by radio to the physician, who
was thus enabled to make a diagnosis.
We now move ships and steer airplanes by radio.
Very recently in Germany, radio was used in
mines underground to locate ores and coal veins ac-
curately, surely a surprising use for the art! In
this invention use is made of a receiving and sending
station, both located underground, one signalling
to the other. When the signals pass through a coal
field, a variation is heard at the receiving end and
by triangulation, the exact location of the coal veins
can be found.
Recently, in Italy, radio has been used for pros-
pecting metal ores. Here the Italian inventors
use very sensitive vacuum tube outfits, and by
means of a certain condenser arrangement, it be-
comes possible to plot accurately the exact location
of the future mine. Today, every radio station has
its ubiquitous a?rial on top of the house. This soon
will be a thing of the past. Already two American
inventors have demonstrated that far better results
may be had by putting the aerial underground. In
their experiments, the inventors use the so-called
underground loops. Of course, these are necessary
THE FUTURE OF RADIO 231
for long distance reception, but for your radio out-
fit on top of the victrola in the parlor, no under-
ground loop, or serial on the roof is necessary. The
serial will be right inside of the outfit. We are al-
ready doing this very thing today, and the outfit
need not be larger than a foot square. That gives
us sufficient space for the concealed serial within the
box. This is not a dream of the future, as it has
already been accomplished for the reception of radio
music over distances of several hundred miles.
It is even possible to do away with the loop en-
tirely. There has appeared lately upon the market,
an electrical plug which is simply screwed into any
lighting fixture in your house. It makes no differ-
ence if your lighting current is 110-volt alternating
current, or 110-volt direct current, or even 220-volts.
This plug consists simply of a condenser arrange-
ment, and the idea of it is as follows : We have seen
in former chapters that any serial wire will pick up
radio waves. Now then, every lighting circuit
forms a sort of loop serial itself. This is particularly
true in the country where the wires run for great
distances out doors. By proper arrangement, as
for instance, using such a plug, the radio waves are
conveyed right over the lighting circuit without in-
terfering with the electric light bulbs, and other elec-
tric appliances in your house. These condenser
plugs are already a great success but they do not
work under all circumstances. For instance, in
apartment houses in which much steel enters into
232 RADIO FOR ALL
their construction, the results are not so good as in
the country where we have a stone or wood
house, and where the electric lighting wires
run outdoors. These condenser plugs work sat-
isfactorily in nearly all instances, even in
apartment houses, in connection with vacuum tube
sets, but they do not work well as a rule with crystal
receivers. Much experimental work is as yet to
be done in this line, but the chances are that ten
years from now, the serial for receiving purposes
will be a thing of the past.
Perhaps the greatest development will be the
radio power transmission of the future. This is, of
course, today, only a dream, but Nikola Tesla has
demonstrated that it can be done, and it is interest-
ing to note that this great savant's ideas are coming
more and more to the front. Dr. Tesla contends
that our radio conceptions are wrong from start to
finish. He claims that it is not the radio waves that
travel through the ether following the curvature of
the earth, but rather currents that travel through the
earth, and we seem to be coming to just this. If
Tesla is right, power transmission by radio should
be a simple thing. It will enable us to tap the earth
at any point and receive our energy to light and heat
our houses. Of course all this is in the future, but
we are surely coming to it.
Another new use for radio is sending pictures,
photographs, etc., through the ether, and the author
believes that he cannot do better than quote part of
THE FUTURE OF RADIO 233
his editorial from the November 1921 issue of
"Recently the signatures of General Foch and
General Pershing were sent across the Atlantic by
radio on the Belin apparatus. There is no good
reason why the amateur cannot do the same thing
for smaller distances at any time.
"In the very near future, the amateur in New
York will buy the first copy of a New York news-
paper, wrap it around his cylinder, and send out a
whole sheet by radio. A thousand miles away an-
other amateur will have a receiving machine that
will reproduce the printed page, type, pictures, and
all in less than a half-hour. This is a thing impossible
to do by ordinary wireless telegraphy, if every word
must be transmitted. The radio picture transmis-
sion solves all this. Thus, in time, a great piece of
news 'breaking' in the city, will be sent broadcast by
the enterprising amateur, who will send the entire
front page of the newspaper, for instance, and the
radio facsimile can then be exhibited in a distant
town from 10 to 24 hours in advance of the receipt
of the actual newspaper.
"All this is not a mere dream, but it already
has been accomplished today. It is up to the ama-
teur to make the thing popular."
To go still a step further, the author in a recent
article in Science & Invention magazine pro-
posed a radio system, which theoretically is
sound. It is nothing else than Television by
234 RADIO FOR ALL
Radio. (Fig. 121). The fundamentals of this pro-
posed scheme are correct, and there is little doubt
that we will have radio television within a very few
years on a scale that will be tremendous. The idea
in short follows:
At the Polo Grounds of New York, let us say,
we have a radio transmitting station in a box-like
affair of about three or four times the size of a
movie camera. We have a box with a lens in front,
the back of the camera being composed of a great
number of photo-el ectric cells. These cells have the
property of passing more or less electric current,
depending upon how much light falls upon the cell.
A strong light will pass much current through a
cell, while a weak light will pass little current. By
means of these cells, we influence a modulator vac-
uum tube connected to the radio transmitter. This
modulator sends out radio waves into space. If a
strong light falls upon the electric cell, No. 1, we
send out a radio wave of a certain intensity at a cer-
tain wave length, let us say 500^ meters. At the
receiving end, this wave is received and is passed
through the regulation radio outfit and thence
through a condenser, vacuum tube and audio-
frequency transformer. This audio-frequency
transformer operates a small magnet which in turn
influences a pivoted diaphragm. This diaphragm
has mounted upon it a strip mirror about y^-
inch long and 1/16-inch wide. Normal and
at rest, a light ray from a common source, let us say
THE FUTUBE OF RADIO
236 RADIO FOR ALL
an electric lamp, directs a single beam of light upon
the diaphragm in such a manner that the light ray
just misses the mirror. The least vibration of the
diaphragm, however, will intercept the light ray and
will reflect it upon a ground glass plate. It is evi-
dent that the more the diaphragm vibrates, the
more the light ray will vibrate back and forward
upon the ground glass screen.
If we now imagine at the sending end several
hundred of the photo-electric cells and at the receiv-
ing end a like number of vibrating mirrors, we can
readily see how a picture sent out from the sender
can be recomposed and reconstructed at the receiver.
It must be understood that our photo-electric cell
sends out its own wave-length. Thus, as mentioned
before, photo-electric cell No. 1 sends out a wave
length of 500y 2 meters. Photo-electric cell No.
2 will send out a wave of 500>4 meters and so on. All
these waves are sent out from the same aerial,
and all the incoming waves are caught upon
the same aerial, each wave operating its own
electro-magnet and consequently the light beam.
We can now see from this how our future
audience will be able to witness a baseball game five
hundred or five thousand miles distant, as if it were
witnessing the game itself. It is, of course, under-
stood that this transmission takes place instantan-
eously, so we will be enabled in the future to view
distant games or other important events at the time
they are taking place. This differs from the movies
THE FUTURE OF RADIO 237
where we are not able to view the events at the time
they take place, but always at a later date. In the
future there will be the possibility of our seeing the
President of the United States make an important
speech, and we will be enabled to not only hear every
word he utters, but see him in person as well.
Of course, it goes without saying that the scheme
here advanced will project the picture in black and
white only. In other words, the picture will look
just like a movie film with the sole difference that
we are witnessing the event at the time it takes place.
Here is an interesting feature of which few peo-
ple are aware. Some months ago, in one of the
writer's editorials he mentioned the fact that radio
waves are eternal, as are light waves; they travel
according to our present conception out into space
at the rate of 186,000 miles a second. We see to-
day the light waves shot off by some far away star,
which light may have originated from that star per-
haps 10,000 or 100,000 years ago. And those light
rays are just coming down to us now. It is the
same with radio waves. Any radio message, any
broadcasted radio selection that is sent out on radio
waves goes out into eternity never to return, never
stopping, ever traveling onward. The thought is
appalling that while you are listening to a famous
operatic star, who is singing from some broadcasting
station, her voice may be heard 100,000 years from
now on some distant planet belonging to its own
little solar system.
238 RADIO FOR ALL
For to believe that there is intelligence only on
this earth is grotesque and foolish in the extreme.
What this superior intelligence, listening to this
broadcasted song will think of it 100,000 years
hence, is difficult to imagine. But, there seems to
be little doubt that this superior intelligence will
smile at the idea of our feeble endeavors. This intel-
ligence will probably view our attempts with the
same amusement as we look upon children using
a string telephone.
At the time this volume is written, radio is just
about twenty-five years old. If we have accom-
plished such wonders in a quarter of a century,
who dares say what will be accomplished in twenty-
five or fifty years more. Our wildest and most im-
possible prophesies will seem feeble. When we,
therefore, say that one of the coming things is trans-
porting solids through space, that is, send-
ing a carload of coal from Pittsburgh to Paris
within a few minutes, all by radio, and all by the
invisible self-same waves, we will probably be laugh-
ed at by our experts. The thing, however, is per-
fectly feasible today, as we shoot solid particles
through glass walls every time an X-ray picture is
taken. X-rays are composed of solid particles which
are just as solid as bricks or lumps of coal. When,
therefore, we are asked what the future of radio is,
we may say in one word, ANYTHING ! There seems
to be nothing impossible that radio cannot accom-
plish in the future:
rporation, Westinghouse Photo
The power plant at the radio broadcasting station WJZ, Newark, N. J. We see here five special
vacuum tubes, each generating about 50 Watts power. This gives a total power of 250 Watts, or
^Kilowatt. On top of the case we see the oscillation transformer which has the function of
adjusting the wave length at which the broadcasting is accomplished, in this case 360 meters.
I he waves emitted by this station have been heard several thousand miles away.
RADIO ACT OF 1912
MISCELLANEOUS RADIO INFORMATION
LIST OF BROADCASTING STATIONS IN UNITED
STATES AND CANADA
UNITED STATES AND POSSESSIONS
The stations listed below send time daily for five minutes, starting
at five minutes before the time set opposite each station. Each tick of
a standard clock is transmitted as a dot, omitting the 29th second of
each minute, the last five seconds of each of the first four minutes,
and finally the last ten seconds of the last minute. A dash is sent at
the time given opposite the station.
9--5S P.M. 10" 20" 30" 40' 50 59*
i ocee<t*e***o*******ooo oo
^THIS DASH -3 DOTS
Station CaH Wave-Length Time
Annapolis, Md ....NSS 17,000 Arc Noon, 10.00 P.M. 75th
meridian standard time.
Arlington, Va NAA 2,650 Spark Noon, 10.00 P.M. 75th
meridian standard time.
Key West, Fla NAR 1,500 Spark Noon, 75th meridian
New Orleans, La.* NAT 1,000 Spark Noon, 75th meridian
Darien, C. Z NBA 10,110 Spark, 5.00 A.M. ; 1.00 P.M.
75th meridian standard
* Time signals not sent on Sundays and holidays.
RADIO FOR ALL
Cavite, Philippine Isl NPO
800 Arc from 23,65 to 24,00 GMT.
952 Spark from 02,55 to 03,00 GMT
and from 13,55 to 14,00
5,000 Arc from 01,55 to 02,00 and
from 14,55 to 15,00 GMT.
1,512 Spark Noon, 120th meridian,
west, standard time.
NPE 2,800 Spark, Noon, 120th meridian,
west, standard time.
San Francisco, Cal NPG 2,400 Spark Noon, 120th meridian,
west, standard time.
San Francisco, Cal NPG 4,800 Arc Noon, 120th meridian,
west, standard time.
Great Lakes, 111.* NAJ 1,512 Spark 11.00 A.M., 90th me-
ridian standard time.
Eureka, Cal.* NPW 2,000 Spark Noon, 120th meridian,
west, standard time.
7,000 Arc 5.00 A.M., 1.00 P.M., 75th
meridian standard time.
1,500 Spark 5.00 A.M., 1.00 P.M.,
75th meridian standard
2,400 Spark Noon, 120th meridian,
west, standard time.
9,800 Arc Noon, 120th meridian
NPM 11,200 Arc 180th meridian, mean
NPM 600 Spark 180th meridian, mean
Cavite, Philippine Isl.
Pt. Arguello, Cal.* . .
North Head, Wash.*
Balboa, Panama NBA
Colon, Panama NAX
San Diego, Cal
San Diego, Cal.* . . .
Pearl Harbor, T. H..
Pearl Harbor, T. H..
SCHEDULE OF WEATHER REPORTS
UXITED STATES AND POSSESSIONS
(75th Meridian Time)
Name of Station
Arlington, Va. NAA 10.30 A.M., Noon, 10 P.M.
Key West, Fla. NAR 10 P.M.
Point Isabel, Tex NAY 12 Midnight
Point Isabel, Tex NAY Noon, 7 P.M.
*Time signals not sent on Sundays and holidays.
RADIO ACT OF 1912 241
Call Broadcasting Hour Wave-
Name of Station Letter (75th Meridian Time) Length
Great Lakes, 111.' NAJ Noon, 10 P.M. 1500
San Juan, P. R.* NAU 10 A.M., 9 P.M., 600 Spark and
San Juan, P. R. NAU When issued and repeated at about
4-hour intervals 2750
Portland, Me NAB Noon, 8 P.M. 1620
Boston, Mass NAD 11. A.M., 5 P.M. 2250
New York, N. Y NAH 10.30 A.M., 5 P.M. 1832
Philadelphia, Pa N A I 10.45 A.M., 5 P.M. 1948
Baltimore, Md NBZ 10.80 A.M., 4 P.M. 700
Norfolk, Va NAM 10.45 A.M., 4 P.M., 8 P.M. 1851
Charleston, S. C., NAO 10.30 A.M., 6 P.M. 2250
Savannah, Ga NEV 11 A.M., 6 P.M. 1813
Jacksonville, Fla N F I 11 A.M., 6 P.M. 450
St. Augustine, Fla NAP 11.30 A.M., 7 P.M. 1851
Miami, Fla. NGE 11.30 A.M., 6 P.M. 1620
St. Petersburg, Fla NGL 11.30 A.M., 7 P.M. 2700
Pensacola, Fla, NAS 11.45 A.M., 6 P.M. 2250
New Orleans, La. NAT 11 A.M., 5 P.M. 1832
Galveston, Tex. NKB 11.30 A. M., 6 P.M. 1813
Alpena, Mich NSM 10.45 A.M., 11.45 A.M.,
4.45 P.M., 7.45 P.M. 1200
Buffalo, N. Y N N Z 10.45 A.M., 4.45 P.M. 1200
Cleveland, Ohio NRH 11 A. M., 5.30 P.M. 1080
Chicago, 111 NUR 11 A.M., 5.30 P.M. 1200
Duluth, Minn. .NUX 10.45 A.M., 4.45 P.M. 2200
Guantanamo, Cuba NAW When issued and repeated at
about 4-hour intervals 2750
Port au Prince, Haiti ....NSC When issued and repeated at
about 4-hour intervals 2250
St. Thomas, V. I. NBB When issued and repeated at
about 4-hour intervals 1688
St. Croix, V. I NNI When issued and repeated at
about 4-hour intervals 450
San Francisco, Cal. ..... .NPH Noon, 10 P.M., 120th Men 950
North Head, Wash NPE Noon, 10 P.M., 120th Mer. 950
San Diego, Cal NPL Noon, 10 P.M., 120th Mer. 950
* Distribution is made from this station from April 15th to De-
"Distribution is made from this station from June to November,
RADIO FOR ALL
NOTE: Noon transmission for Arlington and Great Lakes are
storm warnings, and 10 A.M. and when " issued transmission " for
San Juan are hurricane warnings.
All afternoon and evening transmission listed above, beginning
with Portland, Maine, and ending with St. Croix, V. I., are storm
or hurricane warnings and advices.
ABBREVIATIONS USED IN WEATHER REPORTS
Sydney, N. S S
Nantucket, Mass T
Breakwater, Delaware DB
Hatteras, N. C H
Charleston, S. C C
Key West, Fla. K
Pensacola, Fla P
St. Johns, N. F J
New York, N. Y NY
Lynchburg, Va LB
Cape Henry, Va. CH
Asheville, N. C AV
Atlanta, Ga AT
Jacksonville, Fla. JA
Tampa, Fla TA
Mobile, Ala MO
Burrwood, La BW
Galveston, Tex GV
Brownsville, Tex BV
Fort Worth, Tex FW
Corpus Christi, Tex GV
Kingston, Jamaica KN
Turks Island TI
Havana, Cuba HA
Guantanamo Bay GO
Swan Island SI
San Juan, P. R SJ
St. Thomas, Virgin Isls. . . . . .ST
Basseterre, St. Kitts BT
Roseau, Dominican Republic. .RS
Bridgetown, Barbadoes BB
Santo Domingo, Dominican
Puerto Plata, Dominican
Castries, St. Lucia LU
Willemstadt, Curacao W
Port of Spain, Trinidad PS
Duluth, Minn DU
Marquette, Mich M
Sault Ste. Marie, Mich U
Green Bay, Mich G
Chicago, 111 CH
Alpena, Mich L
Detroit, Mich D
Cleveland, Ohio V
Buffalo, N. Y F
Grand Haven, Mich GH
Father Point, Can FP
Montreal, Canada ML
St. Louis, Mo SL
Little Rock, Ark .LR
Nashville, Tenn N V
Cincinnati, Ohio CN
Tatoosh, Wash T
North Head, Wash NH
Eureka, Cal E
San Francisco, Cal SF
San Diego, Cal SD
RADIO ACT OF 1912 243
ARLINGTON WEATHER REPORT. 2,500 METERS N.A.A.
Sample Report: QSTdeNAA, USWB, SolOSl To2261 DB
0251 H 00844 C 01261 K 004410 P 01243.
QST General call
NAA Arlington Station
USWB U. S. Weather Bureau
S Sydney, Nova Scotia
"010" 30.10 inches, Barometer
8 __ wind Northwest
"1" Light air
T Nantucket, R. I.
"022" 30.22 inches, Barometer
6" _ Southwest wind
"1" Light air
DB Delaware Breakwater
"020" 30.20 inches, Barometer
"5" South wind.
"1" Light air
H Cape Hatteras
008" 30.08 inches, Barometer
"4" Southeast wind
"4" Moderate breeze
C Charleston, S. C.
"012" 30.12 inches, Barometer
6" Southwest wind
"1" Light air
K Key West, Fla.
"004" 30.04 inches, Barometer
"4" Southeast wind
"10" Whole gale.
P Pensacola, Fla.
012" 30.12 inches, Barometer
"4" Southeast wind
3 _ Gentle breezes.
RADIO FOR ALL
BEAUFORT WIND INTENSITY SCALE
Statute Miles Pei
1 Light Air 8
2 Light Breezes 18
3 Gentle Breezes 18
4 Moderate Breezes 23
5 Fresh Breezes 28
6 Strong Breezes 34
7 Moderate Gale 40
8 Fresh Gale 48
9 Strong Gale 56
10 Whole Gale 65
11 Storm 75
12 Hurricane 90
Statute Miles per Hour: 1.15 Nautical M.P.H.
U. S. STATIONS SENDING MARKET REPORTS
Name of Station
Washington, D. C. .
Hazelhurst, N. Y.
Cincinnati, Ohio ..
St. Louis, Mo KDEL
Call- Work Broadcasting Hours
3800 3850 7.30 and 8.00 P.M.
3800 3600 9.00 and 11.00 A.M., 12.00
3000 Noon, 7.30 and 8 P.M.
3800 3675 9.15, 11.30 A.M., 12.30,
3.30,8.15 and 8.45 P.M.
RADIO ACT OF 1912
Name of Station
North Platte, Neb...
Rock Springs, Wyo.. .
Salt Lake City, Utah.
Letters Call- Work Broadcasting Hours
KDEF 2900 4167 9.00, 11.00 A.M., 12.00
Noon, 2.00, 3.00, 5.30,
8.00 and 8.30 P.M.
KDHM 2900 3400 9.30 A.M., 12.00 Noon,
6.00 and 9.00 P.M.
KDHN 2900 3200 9.00 A.M., 12.00 Noon,
6.30,8.00 and 8.30 P.M.
KDEG 2900 3740
KDEH 2200 3600
KDEJ 2200 3400
8.30 A.M., 12.00 Noon,
Reno, Nevada. KDEK 2200 2800 9.00 A.M., and 1.00 P.M.
Stations are also now being installed at Bryan, Ohio, and Iowa
The above stations are all 2-KW Federal arc transmitters and are
not only used for furnishing communications to the Air Mail Service,
but they are also utilized in broadcasting agricultural market reports,
and weather reports. Broadcasts are now being transmitted from
the stations as shown above at the hours listed.
PRESS SCHEDULES C
Washington, D. C
Key West, Fla.
10 P.M., 75th meridian
10 P.M., 75th meridian
10 P.M., 75th meridian
1.15 A.M., local time
11.30 P.M., local time
9.00 P.M., 5 A.M., local
7.30 A.M. (GMT)*
8.00 A.M. (GMT)
6.00 A.M. (GMT)
3.30 A.M. (GMT)
9.00 A.M., 7.00 P.M,
2.00 A.M., 3.30 P.M.
San Francisco, Cal
New York, N. Y
San Diego, Cal
St. Johns, N. F., ,
Barrington Passage, N. F.
Demerara, British Guiana.
Malta (Rinella) .
San Cristobal, Peru
* Greenwich (England) mean time.
RADIO FOR ALL
Hong Kong, China
9.45 P.M. (GMT)
9.15 P.M. (GMT)
8.45 P.M. (GMT)
Aden, British Somaliland.
7.30 P.M. (GMT)
9.45 P.M. (GMT)
10.30 P.M. (GMT)
Durban, South Africa
3.15 P.M. (GMT)
11.30 A.M. (GMT)
7.15 A.M. (GMT)
10.45 A.M. (GMT)
6.30 P.M. (GMT)
7.00 P.M. (GMT)
6.00 P.M. (GMT)
3.30 P.M. (GMT)
4.30 P.M. (GMT)
Woodlark Isl., Australia.
5.00 P.M. (GMT)
3.30 A.M., 3.45
3.00 P.M. (GMT)
8.00 A.M. (GMT)
RADIO CODE ABBREVIATIONS
LIST OF ABBREVIATIONS USED IN RADIO CODE
PRB Do you wish to communi-
cate by means of the Inter-
national Signal Code?...
QRA What ship or coast station
is that 5
ANSWER OB NOTICE
I wish to communicate by means
of the International Signal
QRB What is your distance? ..
QRC What is your true bearing?
QRD Where are you bound for?.
QRF Where are you bound from?
QRG What line do you belong to?
QRH What is your wave-length in
My distance is ....
My true bearing is . . degrees.
I am bound for
I am bound from
I belong to the line.
My wave-length is .... meters.
QRJ How many words have you
to send ?
I have .... words to send.
QRK How do you receive me? . .
QRL Are you receiving badly?
Shall I send 20 ... .
QRM Are you being interfered
QRN Are the atmospherics
I am receiving well.
I am receiving badly. Please
send 20 ... .
I am being interfered with.
QRO Shall I increase power? ..
QRP Shall I decrease power?
QRQ Shall I send faster?
QRS Shall I send slower 5
QRT Shall I stop sending?
QRU Have you anything for me?
QRV Are you ready?
I have nothing for you.
QRW Are you busy?
I am busy (or 4 I am busy with
QRX Shall I stand by?
. . . ). Please do not interfere.
Stand by. I will call you when
RADIO FOR ALL
QRY When will be my turn?.
QRZ Are my signals weak?
QSA Are my signals strong?
( Is my tone bad?..
^ \ Is my spark bad?.
QSC Is my spacing bad? ........
QSD What is your time? ........
QSF Is transmission to be in al-
ternate order or in series?
QSJ What rate shall I collect
QSK Is the last radiogram can-
QSL Did you get my receipt ?
QSM What is your true course?
QSN Are you in communication
QSO Are you in communication
with any ship or station;
(or: with )?
QSP Shall I inform .... that you
are calling him?
QSQ Is .... calling me?
QSR Will you forward the radio-
QST Have you received the gen-
QSU Please call me when you
have finished (or: at ..
ANSWER OR NOTICE
Your turn will be No
Your signals are weak.
Your signals are strong.
The tone is bad.
The spark is bad.
Your spacing is bad.
My time is
Transmission will be in alter-
Transmission will be in series
of 5 messages.
Transmission will be in series
of 10 messages.
The last radiogram is cancelled.
My true course is . . degrees.
I am not in communication with
I am in communication with
(through . . . .)
Inform that I am calling
You are being called by
I will forward the radiogram.
General call to all stations.
Will call when I have finished.
RADIO ACT OF 1912
QSV* Is public correspondence
QSW Shall I increase my spark
QSX Shall I decrease my spark
QSY Shall I send on a wave-
' length of .... meters ? ...
QTC Have you anything for me?
QTE What is my true bearing?
QTF What is my position?
ANSWER OR NOTICE
Public correspondence is being
handled. Please do not
Increase your spark frequency.
Decrease your spark frequency.
Let us change to the wave-
length of . . meters.
Send each word twice. I have
difficulty in receiving you.
Repeat the last radiogram.
Send initials of each word to
I have .... msgs for you (or: I
have something for you.)
Your true bearing is .... de-
Your position is latitude,
* Public correspondence is any radio work, official or private,
handled on commercial wave-lengths.
When an abbreviation is followed by a mark of interrogation, it
refers to the question indicated for that abbreviation.
CAPACITY OF CONDENSERS
To find the capacity of condensers use the following formula:
4 X 3.1416 X T X 900,000
C = Capacity in microfarads.
A = Area in square centimeters of one set of plates or surface.
K = Dielectric constant or specific inductive capacity of the
dielectric used. (Given under " Dielectric Constants.")
T = Thickness of the dielectric between the plates, surfaces
measured in centimeters.
250 RADIO FOR ALL
Capacity of two plates:
2248 X K X A
T X 10*
C is capacity in microfarads.
K is dielectric constant See table.
A is area of plates in square inches.
T is thickness of dielectric in inches.
Capacity of condensers in parallel:
Capacity of condensers in series:
= + + + etc.
C Ci C, C, C
Capacity necessary for any transformer:
_ KW X 10 g
C is capacity in microfarads.
KW is killowatts of power.
E is secondary voltage.
f is frequency of spark discharge.
Inductance of single layer round coil (solenoid) :
0.03948 X A* XN*
Ratio of J* 11 ^
= inductance in cm.
= radius of coil
= number of turns
= length of coil
= is a constant See
RADIO ACT OP 1912 251
TABLE OF "L" SERIAL DIMENSIONS
Approx. Approx. Wave-
Daylight Length with
Reo. Maximum Length
Range Aerial Given
2y 2 -3
WAVE-LENGTHS OF 2ERIALS
To calculate the approximate natural wave-length of an aerial,
the total length of the aerial in feet should be multiplied by the
factor 4.5. This gives the natural wave-length of the aerial in feet.
This result may be divided by 3.28 to obtain the wave-length
Let us take, for example, a flat-top aerial with a length of 100 feet,
connected to a lead-in wire at one end 100 feet long. Then 100 feet
plus 100 feet gives 200 feet, and this multiplied by 4.5 gives 900 feet
as the natural wave-length. Divided by 3.28, we have 274 meters
If the above antenna happened to be connected "T" type, then the
effective radiating length of same would be
1^0 plus 100 = 160 feet.
This value, multiplied by 4.5 gives 675 feet wave-length, which,
divided by 3.28, gives 206 meters.
Range of 4 Ft. Square Loop Aerial
Turin Best Wave-Length Meters
3 250 200-350
4 300 250-400
6 350 300-800
10 600 350-1000
20 1200 900-1800
Range of 6 Ft. Square Loop Aerial
2 220 180-400
6 600 400-900
10 700 600-1200
20 1400 1000-2000
253 RADIO FOR ALL
Spacing for Loops
Size of Loop in Feet Spacing i n Inches
WAVE-LENGTHS AND FREQUENCIES
W.L. Wave-Lengths in Meters. F. Number of Oscillations per
RADIO ACT OF 1912 253
Explanation: A wave of 350 meters will oscillate (vibrate back
and forth) at the rate of 857,100 times in every second.
ENGLISH AND METRIC EQUIVALENTS
1 metre = 39.37 inches
1 cm. = 0.3937 inches
1 foot = 30.48 cms. or 0.3048 meters.
1 inch = 2.54 cms.
1 meter = 100 cms.
DIELECTRIC CONSTANTS "K"
Air 1. Mirror Glass 6.00
Compressed Air 1.004 Common Glass 3.5
Crown Glass 6.96 Mica 8.0
Flint Glass 7.00 Paper 2.5
Plate Glass 8.45 Paraffin 2.25
Mica, therefore, is the highest (best) insulator; it is eight times
better than air.
254 RADIO FOR AIX
The unit of resistance is the ohm. Very large resistances, as for
instance, insulation resistances, are more conveniently reckoned in
Meg-Ohms and very small resistances in Micro-ohms.
1 Meg-ohm = 106 ohms = 1 million ohms.
1 Micro-ohm = 10- 6 ohms = 1 millionth of an ohm.
The unit of current is the ampere, small currents being reckoned
in Milli-amperes or in Micro-amperes.
1 Milli-ampere = 10- 3 ampere = 1 thousandth of an ampere.
1 Micro-ampere = 10- 6 ampere = 1 millionth of an ampere.
The unit of E.M.F. is the volt, small potential differences being
reckoned in Milli-volts or in Micro-volts.
1 Milli-volt = 10-3 volts = 1 thousandth of a volt.
1 Micro-volt = 10-e volts = 1 millionth of a volt.
The unit of quantity is the coulomb, which equals the quantity
of electricity conveyed by a current of one ampere flowing for
The unit of electrical energy is the joule.
The unit of power is the watt, large powers are best reckoned in
Kilo-watts and very small powers in Micro-watts.
1 Kilo-watt = 10 3 watts = 1 thousand watts.
1 Micro-watt = 10- watt = 1 millionth of a watt.
746 watts = 1 H.P.
The unit of capacity is the Farad, smaller units being the micro-
farad and the centimeter.
1 Micro-farad = 10-' farads = 1 millionth of a farad.
900,000 cms = 1 micro-farad.
1 jar = 1,000 cms.
1 Billi-farad = 900 cms.
The unit of inductance is the henry, smaller units being the milli-
henry, the micro-henry and the centimeter.
1 Milli-henry = 10-* henry = 1 thousandth of a henry.
1 Micro-henry = 10-6 henry = 1 millionth of a henry.
1,000 cms. = 1 micro-henry.
1 Coil = 25,000 cms.
RADIO ACT OF 1912
RADIO FOR ALL
FEET PER POUND OF INSULATED
OF INSULATED MAGNET WIRE
Turns per Linear Inch
RADIO ACT OP 1912 257
Turns per Linear Inch
COTTON-COVERED MAGNET WIRE
No. Turns per B. & S.
No. Turns per
Linear Inch Gauge
TUNING COIL DATA
No. of Wire
B. & S. Gauge
Core in Inchn
B s? .
.S*o "ft o^j i^' to v'o.*'
a! \& ?3i M
IRS J*| tit yj
S* *8 B
30 37 58 ..
38 46 73
36 44 46
46 56 58 34
4 in. 700
48 59 46 32
49 60 37 30
6 in. 1000
58 70 37 30
6 in. 1200
55 67 30
63 77 30
find the wave-length in meters of any tuning coil, mul-
in inches by length in meters per
inch of winding.
* Indicates windings suitable for loose coupler primaries.
358 RADIO FOR ALL
The data in this table were compiled for WINDINGS OF EN-
AMELED WIRE ONLY.
Wave-length in meters in above table equals length of wire on
tuning coil in meters multiplied by 4 (not for couplers).
With a Secondary of 2% inches in diameter, shunted by .0005
m. f. Condenser, the following wave-lengths are obtainable:
10 turns 80 to 220 meters
20 turns 120 to 350 meters
30 turns 150 to 420 meters
40 turns 175 to 550 meters
THE RADIO LAW OF 1912
An Act to regulate radio communication, approved August 13, 1912.
Be it enacted by the Senate and House of Repretentativet of the
United Statet of America in Congrett attembled, That a person, com-
pany, or corporation within the jurisdiction of the United States shall
not use or operate any apparatus for radio communication as a means
of commercial intercourse among the several States or with foreign
nations, or upon any vessel of the United States engaged in interstate
or foreign commerce, or for the transmission of radiograms or signals
the effect of which extends beyond the jurisdiction of the State or
Territory in which the same are made, or where interference would be
caused thereby with the receipt of messages or signals from beyond
the jurisdiction of the said State or Territory, except under and in
accordance with a license, revocable for cause, in that behalf granted
by the Secretary of Commerce upon application therefor; but noth-
ing in this Act shall be construed to apply to the transmission and
exchange of radiograms or signals between points situated in the same
State: Provided, That the effect thereof shall not extend beyond the
jurisdiction of the said State or interfere with the reception of radio-
grams or signals from beyond said jurisdiction; and a license shall
not be required for the transmission or exchange of radiograms or
signals by or on behalf of the Government of the United States, but
every Government station on land or sea shall have special call letters
designated and published in the list of radio stations of the United
States by the Department of Commerce. Any person, company or
corporation that shall use or operate any apparatus for radio com-
munication in violation of this section, or knowingly aid or abet an-
other person, company, or corporation in so doing, shall be deemed
guilty of a misdemeanor, and on conviction thereof shall be punished
by a fine not exceeding five hundred dollars, and the apparatus or
RADIO ACT OF 1912 259
device so unlawfully used and operated may be adjudged forfeited to
the United States.
SEC. 2. That every such license shall be in such form as the Secre-
tary of Commerce shall determine and shall contain the restrictions,
pursuant to this Act, on and subject to which the license is granted;
that every such license shall be issued only to citizens of the United
States or Porto Rico or to a company incorporated under the laws
of some State or Territory or of the United States or Porto Rico, and
shall specify the ownership and location of the station in which said
apparatus shall be used and other particulars for its identification
and to enable its range to be estimated ; shall state the purpose of the
station, and, in case of a station in actual operation at the date of
passage of this Act, shall contain the statement that satisfactory proof
has been furnished that it was actually operating on the above-
mentioned date; shall state the wave-length or the wave-lengths
authorized for use by the station for the prevention of interference
and the hours for which the station is licensed for work; and shall
not be construed to authorize the use of any apparatus for radio
communication in any other station than that specified. Every such
license shall be subject to the regulations contained herein, and such
regulations as may be established from time to time by authority of
this Act or subsequent Acts and treaties of the United States. Every
license shall provide that the President of the United States in time of
war or public peril or disaster may cause the closing of any station
for radio communication and the removal therefrom of all radio
apparatus, or may authorize the use or control of any such station or
apparatus by any department of the Government, upon just com-
pensation to the owners.
SEC. 3. That every such apparatus shall at all times while in use
and operation as aforesaid be in charge or under the supervision of
a person or persons licensed for that purpose by the Secretary of
Commerce. Every person so licensed who in the operation of any
radio apparatus shall fail to observe and obey regulations contained
in or made pursuant to this Act or subsequent Acts or treaties of
the United States, or any one of them, or who shall fail to enforce
obedience thereto by an unlicensed person while serving under his
supervision, in addition to the punishments and penalties herein pre-
scribed, may suffer the suspension of the said license for a period to
be fixed by the Secretary of Commerce not exceeding one year. It
shall be unlawful to employ any unlicensed person or for any un-
licensed person to serve in charge or in supervision of the use and
operation of such apparatus, and any person violating this provision
260 RADIO FOR ALL
shall be guilty of a misdemeanor, and on conviction thereof shall be
punished by a fine of not more than one hundred dollars or imprison-
ment for not more than two months, or both, in the discretion of
the court, for each and every such offense: Provided, That in case of
emergency the Secretary of Commerce may authorize a collector of
customs to issue a temporary permit, in lieu of a license, to the
operator on a vessel subject to the radio ship Act of June twenty-
fourth, nineteen hundred and ten.
SEC. 4. That for the purpose of preventing or minimizing inter-
ference with communication between stations in which such apparatus
is operated, to facilitate radio communication, and to further the
prompt receipt of distress signals, said private and commercial
stations shall be subject to the regulations of this section. These regu-
lations shall be enforced by the Secretary of Commerce through the
collectors of customs and other officers of the Government as other
regulations herein provided for.
The Secretary of Commerce may, in his discretion, waive the pro-
visions of any or all of these regulations when no interference of the
character above mentioned can ensue.
The Secretary of Commerce may grant special temporary licenses
to stations actually engaged in conducting experiments for the de-
velopment of the science of radio communication, or the apparatus
pertaining thereto, to carry on special tests, using any amount of
power or any wave-lengths, at such hours and under such conditions
as will insure the least interference with the sending or receipt of com-
mercial or Government radiograms, of distress signals and radio-
grams, or with the work of other stations.
In these regulations the naval and military stations shall be under-
stood to be stations on land.
First. Every station shall be required to designate a certain
definite wave-length as the normal sending and receiving wave-length
of the station. This wave-length shall not exceed six hundred meters
or it shall exceed one thousand six hundred meters. Every coastal
station open to general public service shall at all times be ready to
receive messages of such wave-lengths as are required by the Berlin
convention. Every ship station, except as hereinafter provided, and
every coast station open to general public service shall be prepared to
use two sending wave-lengths, one of three hundred meters and one
of six hundred meters, as required by the international convention in
RADIO ACT OP 1912 261
force: Provided, That the Secretary of Commerce may, in his dis-
cretion, change the limit of wave-length reservation made by regula-
tions first and second to accord with any international agreement to
which the United States is a party.
Second. In addition to the normal sending wave-length all stations,
except as provided hereinafter in these regulations, may use other
sending wave-lengths: Provided, That they do not exceed six hundred
meters or that they do exceed one thousand six hundred meters:
Provided further, That the character of the waves emitted conforms
to the requirements of regulations third and fourth following.
USE OF A "PURE WAVE"
Third. At all stations if the sending apparatus, to be referred to
hereinafter as the " transmitter," is of such a character that the
energy is radiated in two or more wave-lengths, more or less sharply
defined, as indicated by a sensitive wave meter, the energy in no one
of the lesser waves shall exceed ten per centum of that in the greatest.
USE OF A " SHARP WAVE "
Fourth. At all stations the logarithmic decrement per complete
oscillation in the wave trains emitted by the transmitter shall not
exceed two-tenths, except when sending distress signals or signals
and messages relating thereto.
USE OF " STANDARD DISTRESS WAVE "
Fifth. Every station on shipboard shall be prepared to send dis-
tress calls on the normal wave-length designated by the international
convention in force, except on vessels of small tonnage unable to have
plants insuring that wave-length.
SIGNAL OF DISTRESS
Sixth. The distress call used shall be the international signal of
distress ... - ...
USE OF " BROAD INTERFERING WAVE " FOR DISTRESS SIGNALS
Seventh. When sending distress signals, the transmitter of a station
on shipboard may be tuned in such a manner as to create a maximum
of interference with a maximum of radiation.
DISTANCE REQUIREMENT FOR DISTRESS SIGNALS
Eighth. Every station on shipboard, wherever practicable, shall be
prepared to send distress signals of the character specified in regu-
lations fifth and sixth with sufficient power to enable them to be
263 RADIO FOR ALL
received by day over sea a distance of one hundred nautical miles by
a shipboard station equipped with apparatus for both sending and
receiving equal in all essential particulars to that of the station
"BIGHT or WAY" FOR DISTRESS SIGNALS
Ninth. All stations are required to give absolute priority to signals
and radiograms relating to ships in distress; to cease all sending on
hearing a distress signal; and except when engaged in answering or
aiding the ship in distress, to refrain from sending until all signals and
radiograms relating thereto are completed.
REDUCED POWER FOR SHIPS NEAR A GOVERKMEKT STATION
Tenth. No station on shipboard, when within fifteen nautical miles
of a naval or military station, shall use a transformer input exceeding
one kilowatt, nor, when within five nautical miles of such a station, a
transformer input exceeding one-half kilowatt, except for sending
signals of distress, or signals or radiograms relating thereto.
Eleventh. Each shore station open to general public service be-
tween the coast and vessels at sea shall be bound to exchange radio-
grams with any similar shore station and with any ship station with-
out distinction of the radio systems adopted by such stations,
respectively, and each station on shipboard shall be bound to exchange
radiograms with any other station on shipboard without distinction of
the radio systems adopted by each station, respectively.
It shall be the duty of each shore station, during the hours it is
in operation, to listen in at intervals of not less than fifteen minutes
and for a period not less than two minutes, with the receiver tuned to
receive messages of three hundred meter wave-lengths.
DIVISION OF TIME
Twelfth. At important seaports and at all other places where naval
or military and private or commercial shore stations operate in such
close proximity that interference with the work of naval and military
stations can not be avoided by the enforcement of the regulations
contained in the foregoing regulations concerning wave-lengths and
character of signals emitted, such private or commercial shore sta-
tions as do interfere with the reception of signals by the naval and
military stations concerned shall not use their transmitters during the
first fifteen minutes of each hour, local standard time. The Secretary
of Commerce may, on the recommendation of the department con-
cerned, designate the station or stations which may be required to
observe this division of time.
RADIO ACT OF 1912 263
GOVERNMENT STATIONS TO OBSERVE DIVISION OF TIME
Thirteenth. The naval or military stations for which the above-
mentioned division of time may be established shall transmit signals
or radiograms only during the first fifteen minutes of each hour, local
standard time, except in case of signals or radiograms relating to
vessels in distress, as hereinbefore provided.
USE OF UNNECESSARY POWER
Fourteenth. In all circumstances, except in case of signals or
radiograms relating to vessels in distress, all stations shall use the
minimum amount of energy necessary to carry out any communi-
GENERAL RESTRICTIONS ON PRIVATE STATIONS
Fifteenth. No private or commercial station not engaged in the
transaction of bona fide commercial business by radio communication
or in experimentation in connection with the development and manu-
facture of radio apparatus for commercial purposes shall use a trans-
mitting wave-length exceeding two hundred meters, or a transformer
input exceeding one kilowatt, except by special authority of the
Secretary of Commerce contained in the license of the station:
Provided, That the owner or operator of a station of the character
mentioned in this regulation shall not be liable for a violation of the
requirements of the third or fourth regulations to the penalties of one
hundred dollars or twenty-five dollars, respectively, provided in this
section unless the person maintaining or operating such station shall
have been notified in writing that the said transmitter has been found,
upon tests conducted by the Government, to be so adjusted as to
violate the said third and fourth regulations, and opportunity has been
given to said owner or operator to adjust said transmitter in con-
formity with said regulations.
SPECIAL RESTRICTIONS IN" VICINITIES OF GOVERNMENT STATIONS
Sixteenth. No station of the character mentioned in regulation
fifteenth situated within five nautical miles of a naval or military
station shall use a transmitting wave-length exceeding two hundred
meters or a transformer input exceeding one-half kilowatt.
SHIP STATIONS TO COMMUNICATE WITH NEAREST SHORE STATIONS
Seventeenth. In general, the shipboard stations shall transmit their
radiograms to the nearest shore station. A sender on board a vessel
shall, however, have the right to designate the shore station through
which he desires to have his radiograms transmitted. If this can not
264 RADIO FOR ALL
be done, the wishes of the sender are to be complied with only if the
transmission can be effected without interfering with the service of
LIMITATIONS FOR FUTURE INSTALLATIONS IN VICINITIES
OF GOVERNMENT STATIONS
Eighteenth. No station on shore not in actual operation at the
date of the passage of this Act shall be licensed for the transaction
of commercial business by radio communication within fifteen nauti-
cal miles of the following naval or military stations, to wit:
Arlington, Virginia; Key West, Florida; San Juan, Porto Rico; North
Head and Tatoosh Island, Washington; San Diego, California; and
those established or which may be established in Alaska and in the
Canal Zone; and the head of the department having control of such
Government stations shall, so far as is consistent with the transaction
of governmental business, arrange for the transmission and receipt
of commercial radiograms under the provisions of the Berlin con-
vention of nineteen hundred and six and future international
conventions or treaties to which the United States may be a party, at
each of the stations above referred to, and shall fix the rates therefor,
subject to control of such rates by Congress. At such stations and
wherever and whenever shore stations open for general public business
between the coast and vessels at sea under the provisions of the Berlin
convention of nineteen hundred and six and future international con-
ventions and treaties to which the United States may be a party shall
not be so established as to insure a constant service day and night
without interruption, and in all localities wherever or whenever such
service shall not be maintained by a commercial shore station within
one hundred nautical miles of a naval radio station, the Secretary of
the Navy shall, so far as is consistent with the transaction of govern-
mental business, open naval radio stations to the general public
business described above, and shall fix rates for such service, subject
to control of such rates by Congress. The receipts from such radio-
grams shall be covered into the Treasury as miscellaneous receipts.
SECRECY OF MESSAGES
Nineteenth. No person or persons engaged in or having knowledge
of the operation of any station or stations, shall divulge or publish
the contents of any messages transmitted or received by such station,
except to the person or persons to whom the same may be directed, or
their authorized agent, or to another station employed to forward
such message to its destination, unless legally required so to do by the
court of competent jurisdiction or other competent authority. Any
RADIO ACT OF 1912 265
person guilty of divulging or publishing any message, except as herein
provided, shall, on conviction thereof, be punished by a fine of not
more than two hundred and fifty dollars or imprisonment for a period
of not exceeding three months, or both fine and imprisonment, in the
discretion of the court.
For violation of any of these regulations, subject to which a license
under sections one and two of this Act may be issued, the owner of
the apparatus shall be liable to a penalty of one hundred dollars,
which may be reduced or remitted by the Secretary of Commerce, and
for repeated violations of any of such regulations, the license may
For violation of any of these regulations, except as provided in
regulation nineteenth, subject to which a license under section three
of this Act may be issued, the operator shall be subject to a penalty of
twenty-five dollars, which may be reduced or remitted by the Secre-
tary of Commerce, and for repeated violations of any such regulations,
the license shall be suspended or revoked.
SEC. 5. That every license granted under the provisions of this Act
for the operation or use of apparatus for radio communication shall
prescribe that the operator thereof shall not willfully or maliciously
interfere with any other radio communication. Such interference
shall be deemed a misdemeanor, and upon conviction thereof the
owner or operator, or both, shall be punishable by a fine of not to
exceed five hundred dollars or imprisonment for not to exceed one
year, or both.
SEC. 6. That the expression " radio communication " as used in
this Act means any system of electrical communication by telegraphy
or telephony without the aid of any wire connecting the points from
and at which the radiograms, signals, or other communications are
sent or received.
SEC. 7. That a person, company, or corporation within the juris-
diction of the United States shall not knowingly utter or transmit, or
cause to be uttered or transmitted, any false or fraudulent distress
signal or call or false or fraudulent signal, call, or other radiogram of
any kind. The penalty for so uttering or transmitting a false or
fraudulent distress signal or call shall be a fine of not more than two
thousand five hundred dollars or imprisonment for not more than
five years, or both, in the discretion of the court, for each and every
such offense, and the penalty for so uttering or transmitting, or
causing to be uttered or transmitted, any other false or fraudulent
signal, call, or other radiogram shall be a fine of not more than one
RADIO FOR ALL
thousand dollars or imprisonment for not more than two years, or
both, in the discretion of the court, for each and every such offense.
SEC. 8. That a person, company, or corporation shall not use or
operate any apparatus for radio communication on a foreign ship in
territorial waters of the United States otherwise than in accordance
with the provisions of sections four and seven of this Act and so much
of section five as imposes a penalty for interference. Save as afore-
said, nothing in this Act shall apply to apparatus for radio communi-
cation on any foreign ship.
SEC. 9. That the trial of any offense under this Act shall be in the
district in which it is committed, or if the offense is committed upon
the high seas or out of the jurisdiction of any particular State or
district the trial shall be in the district where the offender may be
found or into which he shall be first brought.
SEC. 10. That this Act shall not apply to the Philippine Islands.
SEC. 11. That this Act shall take effect and be in force on and
after four months from its passage.
Approved, August 13, 1912.
U. S. BROADCASTING STATIONS
(Corrected to September 1, 1922)
Letters Name City State
KDKA Westinghouse El. & Mfg.
Co. East Pittsburgh Pa.
KDN Leo J. Meyberg Co. San Francisco Calif.
KDPM Westinghouse Elec. &
Mfg. Co. Cleveland Ohio
KDPT Southern Electrical Co. San Diego Calif.
KDYL Telegram Publishing Co. Salt Lake City Utah
KDYM Savoy Theatre San Diego Calif.
KDYN Great Western Radio
Corp. Redwood City Calif.
KDYO Carlson & Simpson San Diego Cal.
KDYQ Ore. Inst. of Technology Portland Ore.
KDYR Pasadena Star-News
Pub. Co Pasadena Calif.
KDYS The Tribune Great Falls Mont.
KDYU Herald Publishing Co. Klamath Falls Ore.
KDYV Cope & Cornwell Co. Salt Lake City Utah
KDYW Smith, Hughes & Co. Phoenix Ariz.
KDYX Star Bulletin Honolulu Hawaii
JLDYT Rocky Mt. Radio Corp. Denver Colo,
RADIO ACT OF 1912
KDZA Arizona Daily Star
KDZB Frank E. Sicfcrt
KDZD W. R. Mitchell
KDZE The Rhodes Co.
KDZF Auto Club of Southern
KDZG Cyrus Pierce & Co.
KDZH Fresno Evening Herald
KDZI Electric Supply Co.
KDZJ Excelsior Radio Co.
KDZK Nevada Mach. & Elec-
KDZL Rocky Mt. Radio Corp. .
KDZM Hollingworth, E. H.
KDZN Western Radio Corp.
KDZP Newbery Electric Corp.
KDZQ Motor Generator
KDZR Bellingham Publishing
KDZT Seattle Radio Assoc.
KDZW Claude W. Gerdes
KDZX Glad Tidings Tabernacle
KDZZ Kinney Bros. & Sipprell
KFAB Pacific Radiophone Co.
KFAC Glendale Daily Press
KFAD McArthur Bros. Mercan-
KFAE State College of Wash-
KFAF Western Radio Corp.
KFAJ University of Colorado
KFAN The Electric Shop
KFAP Standard Publishing Co.
KFAQ City of San Jose
KFAR Studio Lighting Service
KFAS Reno Motor Supply Co.
KFAT S. T. Donohue
KFAU High School
KFAV Cooke & Chapman
RADIO FOR ALL
KFAW Register Radio Den
KFAY W. J. Virgin Milling Co.
KFBA Ramey & Bryant Radio
KFBB F. A. Buttrey & Co.
KFBC Normal Heights Sta., W.
KFBD Clarence V. Welch
KFBE R. H. Horn, Cline's
KFBF Butte School of Teleg-
KFBG First Presbyterian
KFBH Thomas Musical Co.
KFBJ Idaho Radio Supply Co.
KFBK Kimball-Upson Co.
KFBL Leese Bros.
KFBM Cook & Foster
KFBN Borch Radio Corp.
KFC Northern Radio & Elec.
KFDB John D. McKee
KFI Carl C. Anthony
KFU The Precision Shop
KFV Foster Bradbury Radio
KFZ Doerr-Mitchell Elec. Co.
KGB Wm. H. Mullins Elec. Co.
KGC Elec. Lighting & Elec. Co.
KGF Pomona Fixture & Wir-
KGG Hallock & Watson Radio
KGN Northwest Radio Mfg.
KGO Altadena Radio Labor-
KGU Marion H. Mulrony
KGW Oregonian Publishing Co.
San Luis Obispo
RADIO ACT OF 1912
Letters Name City
KGY St. Martin's College
(Rev. S. Ruth) Lacey
KHD C. F. Aldrich Marble
and Granite Co. Colorado -Springs
KHJ C. R. Kierulff & Co. Los Angeles
KHQ Louis Wasmer Seattle
KJC Standard Radio Co. Los Angeles
KJJ The Radio Shop Sunnyvale
KJQ C. O. Gould Stockton
KJR Vincent I. Kraft Seattle
KJS Bible Inst. of Los Angeles Los Angeles
KLB J. J. Dunn & Co. Pasadena
KLN Hotel Del Monte Del Monte
KLP Colin B. Kennedy Los Altos
KLS Warner Brothers Oakland
KLX Tribune Publishing Co. Oakland
KLZ Reynolds Radio Co. Denver
KMC Lindsay Weatherill & Co. Riedley
KMJ San Joaquin Lt. & Power
KMO Love Electric Co. Tacoma
KNI T. W. Smith Eureka
KNJ Roswell Public Service
KNN Bullock's Los Angeles
KNR Beacon Light Co. Los Angeles
KNT North Coast Products Co. Aberdeen
KNV Radio Supply Co. Los Angeles
KNX Electric Ltg. Supply Co. Los Angeles
KOA Y.M.C.A. Denver
KOB N.M. College Agr. & Mch.
Arts State College
KOE Spokane Chronicle Spokane
KOG Western Radio Electric
Co. Los Angeles
KOJ University of Nevada Reno
KON Holzwasser, Inc. San Diego
KOP Detroit Police Dep't Detroit
KOQ Modesto Evening News Modesto
KPO Hale Brothers San Francisco
KQI Univ. of California Berkeley
RADIO FOR ALL
KQL Arno H. Kluge
KQP Blue Diamond Electric
KQT Elec. Power & Appliance
KQV Doubleday-Hill Elec. Co.
KQW Charles D. Herrold
KQY Stubbs Electric Co.
KRE Maxwell Electric Co.
KSC O. A. Hale & Co.
KSD Post Dispatch
KSL The Emporium
KSS Prest & Dean Radio Co.
KTW First Presbyterian
KUO Examiner Printing Co.
KUS City Dye Works & Laun-
KUY Coast Radio Co.
KVQ J. C. Hobrecht
KWG Portable Wireless Tele.
KWH Los Angeles Examiner
KXD Herald Publishing Co.
KXS Braun Corp.
KYF Thearle Music Co.
KYG Willard P. Hawley, Jr.
KYI Alfred Harrell
KYJ Leo J. Meyberg Co.
KYW Westinghouse Elec. &
KYY Radio Telephone Shop
KZC Pub. Mkt. & Mkt. Stores
KZI Irving S. Cooper
KZM Preston D. Allen
KZN The Deseret News
Salt Lake City
KZV Wenatchee Battery &
RADIO ACT OF 1912
Atl. & Pac. Radio Supply
Ohio Mechanics Institute
St. Louts Chamber of
Union Stock Yds. &
Elliott Electric Co.
Eastern Radio Institute
Minn. Tribune & A.
I. R. Nelson Co.
University of Missouri
Radio Service Co.
W. Va. 360
Otto W. Taylor
New England Motor
Groves Thornton Hdwe.
W. Va. 360
Georgia Radio Co.
Athens Radio Co.
Omaha Grain Exchange
Radio Service Corp.
Yahrling Rayner Music
Midland Refining Co.
Andrew J. Potter
Sterling Electric Co.
Bradley Polytechnic Inst.
Fred M. Middleton
Diamond State Fibre Co.
The Dayton Co.
RADIO FOR ALL
WBAM I. B. Rennyson
WBAN Wireless Phone Corp.
WBAO James Millikin Univer-
WBAP Wortham-Carter Pub. Co.
WBAQ Myron L. Harmon
WBAU Republican Publishing
WBAV Erner & Hopkins
WBAW Marietta College
WBAX John H. Stenger, Jr.
WBAY American Tel. & Tel. Co
WBAZ Times Dispatch Pub. Co.
WBL T. & H. Radio Co.
WBS D. W. May, Inc.
WBT Southern Radio Corp.
WBU City of Chicago
WBZ Westinghouse Elec. &
WCAB Newberg News Ptg. &
WCAC John Fink Jewelry Co.
WCAD St. Lawrence University
WCAE Kaufman & Baer Co.
WCAG Daily States Pub. Co.
WCAH Entrekin Electric Co.
WCAJ Nebraska Wesleyan Univ.
WCAK Alfred P. Daniel
WCAL St. Olaf College
WCAM Villanova College
WCAN Southeastern Radio Tel.
WCAO Sanders & Stayman Co.
WCAP Central Radio Service
WCAQ Tri-State Radio Mfg. &
WCAR Alamo Radio Electric Co.
WCAS Wm. H. Dunwoody ]n-
WCAT So. Dakota School of
N. Y. 360
S. Dak. 485
RADIO ACT OF 1912
J. C. Dice Electric Co.
Q. Herald & Quincy
Elec. Sup. Co.
University of Vermont
Kesselman O'Driscoll Co.
R. E. Compton & Q. Whig
Findley Electric Co.
A. C. Gilbert
University of Texas
Detroit Free Press
Ward Belmont School
H. C. Summers & Son
Illinois Watch Co.
Wm. L. Harrison
Tampa Daily Times
Kansas City Star
J. Lawrence Martin
Mine & Smelter Supply
Hughes Electrical Corp.
Atlanta & West Point
R. R. Co.
Florida Times Union
Glenwood Radio Corp.
Automotive Electric Co.
Mid-West Radio Central,
Hartman Riker Elec. &
Samuel A. Waite
Delta Electric Co.
Slocum & Kilburn
Muskogee Daily Phoenix
N. Y. 360
274 RADIO FOR ALL
WDAW Georgia Rwy. & Power
WDAX First National Bank
WDAY Kenneth M. Hance
WDM Church of the Covenant
WDT Ship Owners' Radio Ser-
WDV Yeiser, John O., Jr.
WDY Radio Corp. of America
WDZ James L. Bush
WEAA Fallian & Lathrop
WEAB Standard Radio Equip.
WEAC Baines Elec. Serv. Co.
WEAD N. W. Kansas Radio
WEAE Virginia Polytechnic Inst.
WEAF Western Electric Co.
WEAH W. Bd. of Trd. & Lander
WEAI Cornell University
WEAJ Univ. of So. Dakota
S. Dak. 360
WEAK Julius B. Abercrombie
WEAM Boro of North Plainfield
WEAN Shepard Co.
WEAO Ohio State University
WEAP Mobile Radio Co.
WEAR Baltimore Amer. & News
WEAS Hecht Co.
WEAT John J. Fogarty
WEAU Davidson Bros. Co.
WEAV Sheridan El. Serv. Co.
WEAW Arrow Radio Labora-
WEAX T. J. M. Daly
WEAY Will Horwitz, Jr.
RADIO ACT OF 1912
WEAZ Donald Redmond
WEH Midland Refining Co.
WEV Hurlburt-Still Electrical
WEW St. Louis University
WEY Cosradio Co.
WFAA A. H. Belo & Co.
WFAB Carl F. Woese
WFAC Superior Radio Co.
WFAD Watson Weldon Motor
WFAF H. C. Spratley Co.
WFAG Radio Engineering Lab-
WFAH Electric Supply Co.
WFAJ Hi Grade Wireless Instr.
WFAK Domestic Electric Co.
WFAL Houston Chronicle Pub.
WFAM Times Pub. Co.
WFAN Hutchinson Elec. Serv.
WFAP Brown's Business College
WFAQ Mo. Wesleyan College &
Cameron Radio Co.
WFAR Hall & Stubs
WFAS United Radio Corp.
WFAT Daily Argus Leader
WFAU Edwin C. Lewis
WFAV University of Nebraska
WFAW Miami Daily Metropolis
WFAX Arthur L. Kent
WFAY Daniels Radio Supply Co.
WFAZ South Carolina Radio
WFI Strawbridge & Clothier
WFO Rike-Kumler Co.
WGAB Q.R.V. Radio Co.
S. Dak. 360
276 RADIO FOR ALL
Letters Name City
WGAC Orpheum Radio Stores
WGAD Spanish American School
of Radio- Telegraphy Ensenada
WGAF Goller Radio Service Tulsa
WGAH New Haven Electric Co. New Haven
WGAJ W. H. Goss Shenandoah
WGAK Macon Electric Co. Macon
WGAL Lancaster Elec. Supply
& Const. Co. Lancaster
WGAM Orangeburg Radio
Equipment Co. Orangeburg
WGAN Cecil E. Lloyd Pensacola
WGAQ Glenwood Radio Corp. Shreveport
WGAR Southwest American Fort Smith
WGAS The Ray-Di-Co Organ-
WGAT American Legion, Dept.
of Nebraska Lincoln
WGAU Marcus G. Limb Wooster
WGAW Ernest C. Albright Altoona
WGAY North Western Radio Co. Madison
WGAZ The South Bend Tribune South Bend
WGF The Register & Tribune Des Moines
WGH Montgomery Light &
Power Co. Montgomery
WGI Amer. Radio Research
Corp. Medford Hillside
WGL Thomas F. J. Hewlett Philadelphia
WGR Federal Tel. & Tel. Co. Buffalo
WGU The Fair Chicago
WGV Interstate Electric Co. New Orleans
WGY General Electric Co. Schenectady
WHA University of Wisconsin Madison
WHAA State University of Iowa Iowa City
WHAB Clark W. Thompson Galveston
WHAC Cole Bros. Electric Co. Waterloo
WHAD Marquette University Milwaukee
WHAE Automotive Electric Ser-
vice Co. Sioux City
RADIO ACT OF 1912
Radio Electric Co.
University of Cincinnati
John T. Griffin
Radio Equipment & Mfg.
Bluefleld Daily Telegraph
Roberts Hdwe. Co.
Phillips Jeffery & Derby
University of Rochester
Southwestern Radio Co.
Frederic A. Hill
Dewey L. Otta
Semmes Motor Co.
Paramount Radio & Elec.
Yale Democrat - Yale
Corinth Radio Supply
Specialty Co., Inc.
Pierce Electric Co.
Holyoke Street Ry. Co.
The Huntington Press
Sweeney School Co.
West Virginia University
Warren R. Cox
Ridgewood Times Ptg. &
Rochester Times Union
Wm. B. Duck Co.
Stuart W. Seeley
Waupoca Civic & Com-
Joslyn Automobile Co.
Ocean City Yacht Club
W. Va. 360
W. Va. 360
W. Va. 860
RADIO FOR ALL
Mrs. Robert E. Zimmer-
Gustav A. De Cortin
Matthews Elec. Supply Co.
Continental Radio &
Heer Stores Co.
Fox River Valley Radio
Standard Service Co.
Chronicle & News
School of Eng. of Mil-
waukee and Wisconsin
Chronicle Publishing Co.
J. A. Rudy & Sons
Burlington Hawkeye &
Home Electric Co.
Leon T. Noel
American Trust & Sav-
New York Radio Labor-
Saginaw Radio & Elec-
Capital Radio Co. (Paul
Woodward & Lothrop
Electric Supply Sales Co.
K. & L. Electric Co.
Continental Elec. Sup. Co.
Cincinnati Radio Mfg.
American Radio Co.
Jackson's Radio Engi-
RADIO ACT OF 191*
WJAE The Texas Radio Syndi-
WJAF Muncie Press-Smith Elec-
WJAG Norfolk Daily News
WJAH Central Park Amuse-
WJAK White Radio Labora-
WJAL Victor Radio Corp.
WJAM D. M. Perham
WJAN Peoria Star-Peoria Radio
WJAP Kelley-Duluth Co.
WJAQ Capper Publications
WJAR The Outlet Co.
(J. Samuels & Bro.)
WJAS Pittsburgh Radio Supply
WJAT Kelley-Vawter Jewelry
WJAU Yankton College
WJAX Union Trust Co.
WJAZ Chicago Radio Labo-
WJD Richard H. Howe
WJH White & Boyer Co.
WJK Service Radio Equip. Co.
WJT Electric Equipment Co.
WJX DeForest Radio Tel. &
WJZ Westinghouse Elec. &
WKAA H. F. Paap
WKAC Star Publishing Co.
WKAD Chas. Looff
WKAF W. S. Radio Supply Co.
WKAG Edwin T. Bruce, M.D.
WKAH Planet Radio Co.
Stockdale Ohio 360
Portland Me. 360
Cedar Rapids Iowa 360
R. I. 360
West Palm Beach Fla.
280 RADIO FOR ALL
Fargo Plumbing and
N. Dak. 360
Okfuskee County News
Gray & Gray
Hastings Daily Tribune
Alabama Radio Mfg. Co.
Dutee W. Flint
R. I. 360
Radio Corp. of Porto
P. R. 360
L. E. Lines Music Co.
Laconia Radio Club
N. H. 360
Turner Cycle Co.
Wm. A. MacFarland
London's Music and
Joseph M. Zamoiski Co.
Riechman Crosby Co.
Oklahoma Radio Shop
George F. Grossman
North Carolina State
N. C. 360
Arvanette Radio Supply
Johnson Radio Co.
N. Y. 360
Waco Electrical Supply
University of Minnesota
Hamilton Mfg. Co.
Crosley Mfg. Co.
Atchinson County Mail
General Supply Co.
Beaumont Radio De-
Auburn Electrical Co.
RADIO ACT OF 1912
WMC Columbia Radio Co.
WMH Precision Equipment Co.
WMU Doubleday-Hill Electric
WNAL R. J. Rockwell
WNJ Shotton Radio Mfg. Co.
WNO Wireless Tel. Co. of Hud-
WOC Palmer School of Chiro-
WOE Buckeye Radio Service
WOH Hatfield Electric Co.
WOI Iowa State College
WOK Pine Bluff Co.
WOO John Wanamaker
WOQ Western Radio Co.
WOR L. Bamberger & Co.
WOS Mo. State Marketing
WOU Metropolitan Utilities
WOZ Palladium Printing Co.
WPA Fort Worth Record
WPE Central Radio Co.
WPG Nushawg Poultry Farm
WPI Electric Supply Co.
WPJ St. Joseph's College
WPL Fergus Electric Co.
WPM Thomas J. Williams
WPO United Equipment Co.
WRK Doron Bros. Electric Co.
WRL Union College
WRM University of Illinois
WRP Federal Inst. of Radiotel.
WRR D. Police & Fire Signal
WRW Tarrytown Radio Re-
WSB Atlanta Journal
WSL J. & M. Electric Co.
m RADIO FOR ALL
Ship Owners' Radio Ser-
L. M. Hunter & G. L.
Erie Radio Co.
Alabama Power Co.
Kansas State Agric. Col-
Paris Radio Electric Co.
George M. McBride
Daily News Printing Co.
Ford Motor Co.
McCarthy Bros. & Ford
CANADIAN BROADCASTING STATIONS
Calgary Daily Herald
Toronto Daily Star
Marconi W. Co. of Can.,
The Morning Albertan
Metropolitan Motors Co.
News Publishing Co.,
T. Eaton Co.
London Free Press
Tribune Newspaper Co.
Can. Independent Tel. Co.
Marconi W. Tel. Co.
1 VANCOUVER, B.C.
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""PARIS 1 "! BLUFF * MlS ,,ss 1 pp. '*> A 8 * MA \ o R ' *N
"A" Battery, 223
Abbreviations, 242, 247
Accessories Vacuum Tube, 85
Aerial, 20, 21, 30, 31, 32, 83, 47,
106, 108, 110, 112, 117, 121,
122, 125, 127, 128, 130, 131,
132, 137, 231, 250
Aerial, Concealed, 231
Aerial Circuit, 106
Aerial Dimensions, 250
Aerial, Four-wire, 110, 117
Aerial, Height of, 112
Aerial Indoor, 33
Aerial, Inverted L, 132
Aerial, Outdoor, 47
Aerial, Single, 110, 121
Aerial, Single-wire, 121
Aerial, T Type, 131
Aerial, Two- and Four-wire, 116
Aerial, Umbrella, 122
Aerial, Underground, 128, 129 %
Aerials, Loop, 108, 125, 127, 250
Aerials, T, 131
Aerials, Wave Lengths of, 130
Amplification, Audio, 93
Amplifier, 45, 69, 87, 96, 98, 170,
Amplifier Rheostat, 226
Amplifier, Two-Stage, 220
Amplifier, Two-Step, 87
Amplifier, Voice, 170
Amplifiers, Audio Frequency, 96
Amplifiers, Tone, 98
Amplifying Transformers, 224
Analogy in Tuning, 104
Antenna, 31, 142, 117, 119, 142,
Antenna Connector, 117, 119
Antenna, Transmitting Stations,
Antennae, Loop, 250
Arc, Electric, 37, 164, 165
Arc Transmitted, 165
Argentiferous Galena, 63
Arresters, Lightning, 139
Atmospheric Electricity, 37, 49,
60, 66, 130, 139, 142
Audio Amplification, 93
Audio Frequency Amplifiers, 96
Audio Frequency Transformer,
Audion, 43, 66, 194
Audion Bulb, 209
"B" Battery, 89, 211, 223, 225
Bakelite, 205, 212
Bakelite Dials, 212
Bakelite Panel, 209
Balanced Circuit, 73
Balls, Zinc, 30
Bank-wound Coil, 209
Battery "A," 223
Bell, 19, 23
Bell, Ringing, 19
Binding Posts, 198, 208, 222
Broadcasted Entertainment, 174
Broadcasting, 20, 27, 43, 168, 170,
174, 177, 239, 244, 263, 266, 267
Broadcasting Hour, 240, 244
Broadcasting Music, 174
Broadcasting Station, 20, 27, 43,
168, 170, 174, 239, 263, 266,
Broadcasting Stations, Cana-
Broadcasting Stations, U. S., 266
Broad Interfering Wave, 261
Bulb, Audion, 209
Buzzer, 190, 193, 197
Buzzer, Test, 197
Call Letters, 240, 244
Canadian Broadcasting Stat-
Capacity, 196, 249, 253, 254
Capacity, Condenser, 196, 253
Carbon Detector, 53
Carbon Tetrachloride, 64
Carborundum Crystal, 58
Carborundum Detector, 68
Cardboard Tubes, 214
Carrier Wave, Radio, 25
Catwhisker, 62, 65, 66, 184
Cells, Photo-Electric, 234, 236
Circuit, Aerial, 106
Circuit, Balanced, 73
Circuit, Oscillating, 165
Clamp, Ground, 133, 134, 136
Close Wave Length, 77
Code, 34, 35, 36, 42, 247
Code, Continental, 34
Code, Radio, 247
Code, Telegraphic, 34, 86
Codes, Wireless, 35
Coherer, 12, 40, 43, 51, 63
Coherer, Marconi, 43, 53
Coil, 187, 192, 196, 209
Coil, Bank-wound, 209
Coil Data, Tuning, 257
Coil, Loop, 209
Coil, Secondary, 192, 217
Coil, Sending Tuning, 33
Coil, Spark, 11, 30, 40
Coil, Tap, 182
Coil, Tickler, 226
Coil, Tuning, 83, 84, 70, 71, 73,
Coils, 214, 217
Cold Plate, 68
83, 107, 196
Compass, Radio, 126
Compass Station, 125
Concealed Aerial, 231
Condenser Capacity, 196, 253
Condenser, Fixed, 81, 85, 195,
Condenser, Grid, 210, 225
Condenser, Grid Leak, 93
Condenser, Phone, 84
Condenser Plugs, 231, 232
Condenser, Stopping, 207
Condenser, Variable, 82, 83, 85,
107, 138, 195, 208, 209
Condensers, 79, 80, 81, 82, 83, 84,
85, 93, 106, 107, 138, 189, 195,
196, 207, 208, 209, 210, 225, 249
Connector, Antenna, 117, 119
Constants, Dielectric, 249, 252
Continental Code, 34
Continuous Waves, 13, 25, 37, 38,
Cooper Wire Tables, 255
Copper Pyrite, 62
Copper-clad Wire, 109
Cotton, Double Wire, 256
Cotton-covered Magnet Wire,
Cotton, Single Wire, 256
Coupler, Vario-, 79, 212
Couplers, Loose, 73, 75, 76, 77
212, 216, 217, 218
Crystal, 64, 65, 184, 189, 197, 199,
Crystal, Carborundum, 68
Crystal Detector, 43, 58, 68, 72
Crystal Outfit, 180
Crystal Pressure, 59
Currents, High Frequency, 68,
Currents, Voice, 170
Data, Tuning Coil, 257
De Forest, 68
Detectors, 40, 43, 44, 53, 54, 56,
67, 58, 59, 60, 63, 68, 72, 193,
Detector, Carbon, 63
Detector, Carborundum, 58
Detector, Crystal, 43, 58, 68, 72
Detector, Electrolytic, 54, 56, 57
Detector, Radiocite, 63
Detector, " Rasco," 199
Detector, Silicon, 69, 60, 61
Detector, Vacuum Tube, 44
Device, Protective, 141, 146
Devices, Tuning, 70
Diagnosis, Radio, 230
Diagram, Radio, 149
Dials, Bakelite, 212
Dielectric Constants, 249, 252
Dimensions, Aerial, 250
Distance, Transmitting, 40
Distress Signals, 24, 35, 261
Distress Wave, Standard, 261
Division of Time, 262
Double Cotton-covered Magnet
Double Cotton Wire, 256
Double Silk Wire, 256
Doughnut Type Coil, 192
Edison, 66, 67
Edison Effect, 67
Effect, Inductive, 73
Effect, Regenerative, 226
Efficient Receiver, 206
Electric Arc, 37, 164, 165
Electric Cells, Photo-, 234, 236
Electric Spark, 11
Electric Waves, 11
Electrical Microphones, 21, 165,
166, 173, 174, 178
Electrical Units, 254
Electricity, Atmospheric, 37, 49,
60, 66, 130, 139
Electricity, Static, 37, 49, 50, 66,
130, 139, 142
Electrolytic Detector, 54, 5, 57
Electrons, 67, 68, 91
E. M. F., 254
Enameled Wires, 201, 256
Entertainment, Broadcasted, 174
Eternal Radio Waves, 237
Fading Signals, 115
Fessenden, Reginald, 166
Filament, 67, 68, 69, 90, 209, 223
Filament Voltage, 224
Fixed Condenser, 81, 85, 195, 207
Force, Electro-Motive, 254
Four-wire Aerial, 110, 117
Frequencies, Wave Lengths and,
Frequency Amplifiers, Audio, 94
Frequency Currents, High, 68,
Frequency Transformer, Audio,
Frequency Transformer, Radio,
Fundamental Note, 81
Future of Radio, 229
Galena, Argentiferous, 63
Galena, 63, 193, 197, 199, 203, 207
Gap, Quenched Spark, 37
General Receiving, 42
General Transmitting, 80, 37, 40
Government Stations, 263
Grand Opera by Wireless, 178
Grid, 67, 69, 223
Grid Condenser, 210, 226
Grid Leak, 91, 92, 225
Grid Leak Condenser, 93
Ground Clamp, 133, 134, 136
Ground, Operating, 144
Ground Wire, 134, 141, 142, 143,
Ground Wire, Operating, 144
Ground Wire, Protective, 143,
Ground Wire, Receiving Equip-
Grounding Rod, 136
Grounding Switch, Protective,
Grounds, 108, 133, 136
Height of Aerial, 112
High Frequency Currents, 68,
High Power, 44
Hour, Broadcasting, 240, 244
Impure Wave, 31
Inductance, 203, 204, 253, 254
Inductive Effect, 73
Information, Radio, 239
Instruments, Receiving, 51
Insulators, 112, 118
Intensity Scale, Wind, 244
Interference, 76, 123
Interfering Wave, Broad, 2fll
Interrupted Spark Wave, 13, 38,
Interrupted Waves, 13, 38, 39,
Inverted L Aerial, 132
Inverted L Type, 116
Invisible Sound Waves, 18
Iron Pyrite, 62
Jumper Wire, 223
Key, 24, 34
Kilowatt, 39, 254
L Aerial, Inverted, 132
L Type, Inverted, 116
Law of 1912, Radio, 258
Lead-in, 110, 119, 120, 141, 142,
Lead-in Wires, 141, 142, 146, 201
Leak, Grid, 91, 92, 225
Length, Wave, 22, 23, 27, 84, 70,
77, 105, 130, 131, 244, 250, 251,
Letters, Call, 240 244
Lattice Type, 209
Lightning Arresters, 139
Lightning Regulations, 140
Litz Wire, 209
Locate Ores, Radio to, 230
Loop Aerials, 108, 125, 127, 250
Loop Antennae, 250
Loop Coil, 209
Loops, Underground, 230
Loose Couplers, 73, 75, 76, 77, 212
216, 217, 218
Loud Speakers, 98
Low Priced Receiving Set, 193
Magnavox, 97, 226
Magnet Wire, 256
Magnet Wire, Double Cotton-
Marconi, Guglielmo, 12, 31, 34, 36
37, 43, 52, 63
Marconi Coherer, 53
Market Reports, 244
Messages, Secrecy of, 264
Metal Pellet, 65
Micro-farads, 249, 254
Microphones, Electrical, 21
Misconception, Radio, 27
Modulator Tube, 171
Motive-Force, Electro-, 254
Music, Broadcasting, 174
Music, Radio, 175
Natural Wave Lengths, 131
Night Time Reception, 48
1912, Radio Law of, 258
Normal Wave Length, 260
Note, Fundamental, 31
Ohm, 254, 255
$1.00 Radio Set, 198
Opera by Wireless, Grand, 178
Operating Ground, 144
Operating Ground Wire, 144
Ores, Radio to Locate, 230
Oscillating Circuit, 165
Outdoor Aerial, 47
Outfit, Crystal, 180
Outfits, Simple Receiving, 180
Panel, 212, 223
Panel, Bakelite, 209
Paper, Paraffined, 195
Paraffined Paper, 195
Pellet, Metal, 65
Performances, Radio, 177
Phone Condenser, 84
Photo-Electric Cells, 234, 236
Pickard, Greenleaf W., 62,
Picture Transmission, Radio, 233
Pictures, Radio Sending, 232
Pipe, Water, 106
Plate, 67, 68, 69, 223
Plate, Cold, 68
Plugs, Condenser, 231, 232
Pocket Size Receiving Set, 192
Points, Sensitive, 63
Points, Switch, 207
Portable Receiving Set, 208, 209
Posts, Binding, 198, 208, 222
Poulsen, Valdemar, 13, 164
Power, 39, 40, 41, 44
Power, High, 44
Power Transmission, Radio, 232
Press Schedules, 245
Pressure, Crystal, 59
Primaries, 215, 217, 218
Primary, 75, 76, 192
Principle of Transformer, 73
Private Stations, 263
Prospecting, Radio, 230
Protective Device, 141, 146
Protective Ground Wire, 143,
Protective Grounding Switch,
Pure Wave, 261
Pyrite, Copper, 62
Pyrite, Iron, 62
Quenched Spark Gap, 37
Radio Carrier Wave, 25
Radio Code, 247
Radio Compass, 126
Radio Diagnosis, 230
Radio Diagrams, 149
Radio Frequency Transformer,
Radio, Future of, 229
Radio Law of 1912, 258
Radio Music, 175
Radio Performances, 177
Radio Picture Transmission, 133
Radio Power Transmission, 232
Radio Prospecting, 230
Radio Sending Pictures, 232
Radio Set, $1.00, 198
Radio Signals, 46
Radio Telephone, 166, 167
Radio Telephone Daily, 229
Radio Telephony, 42, 164, 166,
Radio Television, 234
Radio to Locate Ores, 230
Radio Wave, 14, 21, 26, 27, 34,
232, 237, 261
Radio Waves, Eternal, 237
Radiocite Detector, 63
Radiophone Receiver, Simple,
Radiophone Receiver, Simplest,
"Radioson" Detector, 57
Receiver, Efficient, 205
Receiver, Simple Radiophone,
Receiver, Simplest Radiophone,
Receiver, Short Wave Regen-
Receivers, Telephone, 66, 96
Receiving Equipment Ground
Receiving (General), 42
Receiving Instruments, 51
Receiving Outfits, Simple, 180
Receiving Set, 47, 192, 193, 208,
Receiving Set, Low-priced, 193
Receiving Set, Pocket Size, 192
Receiving Set, Portable, 208, 209
Receiving Station, 42
Receiving Transformer, 192
Reception, Night Time, 48
Regenerative Effect, 226
Regenerative Receiver, Short
Regulations, Lightning, 140
Reports, Market, 244
Reports, Weather, 240, 242, 243
Rheostat, 90, 209, 222
Rheostat, Amplifier, 226
Rheostats, 90, 209, 222
Ring Wound Coil, 192
Ringing Bell, 19
Rod, Grounding, 136
Scale, Wind Intensity, 244
Schedules, Press, 245
Secondary, 75, 76, 192, 215, 216,
Secondaries, 216, 218
Secondary Coil, 192, 217
Secrecy of Messages, 264
Sending, 33, 39
Sending Pictures, Radio, 232
Sending Station, 27
Sending Tuning Coil, 33
Sensitive Points, 63
Sensitivity, 44, 62
Set, $1.00 Radio, 198
Set, Low-priced Receiving, 193
Set, Pocket Size Receiving, 192
Set, Portable Receiving, 208
Set, Receiving, 47, 192, 193, 198,
Sharp Tuning, 226
Sharp Wave, 261
Shellac, 188, 216
Short Wave, 211
Short Wave Regenerative Re-
Signals, Distress, 24, 35, 261
Signals, Fading, 115
Signals, Radio, 46
Signals, Telegraphic, 24
Signals, Time, 240
Silk, Double Wire, 256
Silk, Single Wire, 256
Silicon Detector, 59, 60, 61
Simple Radiophone Receiver,
Simple Receiving Outfits, 180
Simplest Radiophone Receiver,
Simple Tuner, 203
Single Aerial, 110, 121
Single Cotton Wire, 256
Single Silk Wire, 256
Single Vacuum Tube, 46
Single-wire Aerial, 121
Slider, 33, 70, 71, 72, 75, 102
Slider, Tuning Coil, 102
Socket, 209, 224, 225
Sound, 20, 42
Sound Waves, 16, 26
Sound Waves, Invisible, 18
Spark Coil, 11, 30, 40
Spark, Electric, 11, 30, 36
Spark Gap, Quenched, 37
Spark Stations, 245
Spark Wave, Interrupted, 39
Speakers, Loud, 97
Speed of Waves, 26
Standard Distress Wave, 261
Static, 37, 49, 50, 66, 130, 139
Static Electricity, 37, 49, 50, 66,
Static Surges, 66
Station, Broadcasting, 20, 27, 43,
168, 170, 174, 239, 263, 266,
Station, Compass, 125
Station, Receiving, 42
Station, Sending, 27
Stations, Government, 263
Stations, Private 263
Stations, Spark, 245
Step, Three-, 69
Step, Two-, 69
Stopping Condenser, 207
Surges, 144, 148
Surges, Static, 66
Switch Points, 207
Switch, Protective Grounding,
T Aerials, 131
T Type Aerial, 131
Tables, Cooper Wire, 255
Tap Coil, 182
Telegraphic Code, 34, 36
Telegraphic Signals, 24
Telephone Daily, Radio, 229
Telephone, Radio, 42, 164, 166,
Telephone Receivers, 56, 96
Telephone Transmitter, 166
Telephony, Radio, 42, 164, 166,
Television, Radio, 234
Test Buzzer, 197
Tetrachloride, Carbon, 64
Three-Slide Tuners, 73
Tickler Coil, 226
Time, Division of, 262
Time Signals, 239
Tinfoil, 195, 197
Tone Amplifiers, 98
Transformer, Audio Frequency,
Transformer, Principle of, 73
Transformer, Radio Frequency,
Transformer, Receiving, 192
Transformers, Amplifying, 224
Transmission, Radio Picture, 233
Transmission, Radio Power, 232
Transmitter, 40, 165, 166,
Transmitter, Arc, 165
Transmitter, Telephone, 166
Transmitters of Waves, 18
Transmitting Distance, 40
Transmitting (General), 30, 37
Transmitting Stations Antenna,
Transmitting Tubes, 171
Tube Accessories, Vacuum, 85
Tube, Modulator, 171
Tube, Vacuum, 43, 46, 66, 67,
68, 69, 85, 171
Tubes, Cardboard, 214
Tubes, Transmitting, 171
Tuner, Simple, 203
Tuners, Three-Slide, 73
Tuning, 32, 70, 73, 76, 77, 101,
Tuning, Analogy in, 104
Tuning Coil, 33, 34, 70, 71, 73, 83,
102, 103, 107, 196, 207, 257
Tuning Coil Data, 257
Tuning Coil, Sending, 33
Tuning Coil Slider, 102, 103
Tuning Devices, 70
Tuning Out, 28
Tuning, Sharp, 76, 77, 226
Two- and Four-wire Aerial, 116
Two-Stage Amplifier, 220
Two-Step Amplifier, 87
Type, Coil Doughnut, 192
Type, Inverted L, 116
Type, Lattice, 209
Umbrella Aerial, 122
Underground Aerial, 128, 129,
Underground Loops, 230
Units, Electrical, 254
U. S. Broadcasting Stations, 266
Vibrations, 25, 42
Vacuum Tube, 43, 46, 66, 67, 68,
69, 85, 171
Vacuum Tube Accessories, 85
Vacuum Tube Detector, 44,
Vacuum Tube, Single, 46
Values, Variocoupler, 258
Variable Condenser, 82, 83, 85,
107, 138, 195, 208, 209
Vario-coupler, 79, 212
Variocoupler Values, 258
Variometers, 78, 212, 215, 216,
Voice Amplifier, 170
Voice Currents, 170
Voltage, Filament, 224
Water Pipe, 106
Water Waves, 16
Wave, Broad Interfering, 261
Wave, Impure, 31
Wave Interrupted Spark, 89
Wave Length, 22, 23, 27, 34, 70
77, 105, 130, 131, 244, 250, 251,
Wave Length, Close, 77
Wave Length, Normal, 260
Wave Lengths of Aerials, 130
Wave Lengths and Frequencies,
Wave Lengths, Natural, 131
Wave, Pure, 261
Wave, Radio, 14, 21, 26, 27, 34,
Wave, Radio Carrier, 25
Wave, Sharp, 261
Wave, Short, 211
Wave, Standard Distress, 261
Waves, 11, 13, 14, 16, 18, 21, 25,
26, 27, 31, 34, 37, 38, 39, 43, 47
130, 131, 165, 211, 244, 250, 251,
Waves, Continuous, 13, 25, 37, 38,
Waves, Electric, 11
Waves, Eternal Radio, 237
Waves, Interrupted, 13, 38
Waves, Invisible Sound, 18
Waves, Radio, 232, 237
Waves, Sound, 16, 26
Waves, Speed of, 26
Waves, Transmitters of, 18
Waves, Water, 16, 237, 261
Weather Reports, 240, 242, 243
Winding, 207, 216
Wind Intensity Scale, 244
Wire, Copper-clad, 109
Wire, Double Cotton-covered
Wire, Enameled, 256
Wire, Ground, 134, 141, 142, 143,
Wireless Codes, 35
Wireless, Grand Opera by, 178
Wire, Litz, 209
Wire, Magnet, 256
Wire, Operating Ground, 144
Wire, Protective Ground, 143,
Wire, Receiving Equipment
Wires, Enameled, 201
Wires, Lead-in, 141, 142, 146, 201
Wire Tables, Cooper, 255
Wire, Wollaston, 54, 56, 57
Wollaston Wire, 54, 56, 57
Wound, Ring Coil, 192
Zinc Balls, 30
This book is DUE on the last date stamped below.
AA 000972755 3